View source for Strategic Defense Initiative

{{Short description|U.S. military defense program (1984–1993)}}
{{Redirect|Star Wars program|the media franchise|Star Wars}}
{{Use mdy dates|date=December 2019}}
{{Use American English|date=June 2022}}

{{citations needed|date=June 2024}}
{{Infobox government agency
|agency_name     = Strategic Defense Initiative Organization
|logo            =
|logo_width      = 140pxr
|logo_caption    = Logo
|seal            = SDI_Logo.svg
|seal_width      =
|seal_caption    =
|formed          = 1984
|dissolved       = 1993 (renamed)
|preceding1      = [[Ballistic Missile Defense Organization]]
|preceding2      =
|superseding     = Ballistic Missile Defense Organization<br />[[Missile Defense Agency]]
|jurisdiction    = [[Federal government of the United States]]
|headquarters    =
|employees       =
|budget          =
|child2_agency   =
|website         =
|footnotes       =
}}
The '''Strategic Defense Initiative''' ('''SDI'''), derisively nicknamed the '''[[Star Wars]] program''', was a proposed [[missile defense]] system intended to protect the United States from attack by [[Ballistic missile|ballistic]] [[strategic nuclear weapon|nuclear missile]]s. The program was announced in 1983, by President [[Ronald Reagan]].<ref name="fas_milestones">{{cite web|author=Federation of American Scientists|url=https://fas.org/spp/starwars/program/milestone.htm |title=Missile Defense Milestones|archive-url=https://web.archive.org/web/20160306023546/http://fas.org/spp/starwars/program/milestone.htm |archive-date=March 6, 2016 |access-date= March 10, 2007}}</ref> Reagan called for a system that would render [[nuclear weapon]]s obsolete, and to end the doctrine of [[mutual assured destruction]] (MAD), which he described as a "[[suicide pact]]".<ref>{{cite web|url=https://www.atomicheritage.org/history/strategic-defense-initiative-sdi|title = Strategic Defense Initiative (SDI)}}</ref> Elements of the program reemerged in 2019 under the [[Space Development Agency]] (SDA).<ref>{{cite web |url=https://www.science.org/content/article/decades-after-reagan-s-star-wars-trump-calls-missile-defenses-would-blast-warheads-sky |title=Decades after Reagan's 'Star Wars,' Trump calls for missile defenses that would blast warheads from the sky |first=Gabriel|last=Popkin|date=22 January 2019}}</ref>

The Strategic Defense Initiative Organization (SDIO) was set up in 1984 within the [[US Department of Defense]] to oversee development. Advanced weapon concepts, including lasers,<ref>{{Cite book |editor-last=Wang |editor-first=C. P. |url={{google books|plainurl=yes|id=HKspAQAAMAAJ}}|title=Proceedings of the International Conference on Lasers |date=1985 |publisher=STS Press |language=en}}</ref><ref name=Lasers87>{{Cite book |last=Japan |first=High Temperature Society of |url={{google books|plainurl=yes|id=Uw1ZAAAAYAAJ}} |title=Proceedings of the International Conference on Laser Advanced Materials Processing--Science and Applications|date=21 May 1987 |publisher=High Temperature Society of Japan |language=en|editor-first=F. J. |editor-last=Duarte|editor-link=F. J. Duarte}}</ref> [[particle-beam weapon]]s, and ground and space-based missile systems were studied, along with sensor, [[command and control]], and computer systems needed to control a system consisting of hundreds of combat centers and satellites spanning the globe. The US held a significant advantage in advanced missile defense systems through decades of extensive research and testing. Several concepts, technologies and insights obtained were transferred to subsequent programs.<ref>{{cite web|first1=James A. |last1=Abrahamson|first2=Henry F. |last2=Cooper|title=What Did We Get For Our $30-Billion Investment In SDI/BMD?|url=http://highfrontier.org/wp-content/uploads/2016/08/What-for-30B_.pdf |date=September 1993|access-date=November 20, 2022}}</ref><ref>{{cite web|author=Steven Pifer |url=https://www.brookings.edu/opinions/the-limits-of-u-s-missile-defense/ |title=The limits of U.S. missile defense |publisher=Brookings.edu |date=2015-03-30 |accessdate=2022-03-14}}</ref><ref>{{cite journal|title=Did Star Wars Help End the Cold War? Soviet Response to the SDI Program|first=Pavel |last=Podvig|url=https://scienceandglobalsecurity.org/archive/sgs25podvig.pdf |journal=Science & Global Security |volume=25|number=1,3–27|access-date=November 20, 2022}}</ref><ref>{{cite web|url=https://carnegieendowment.org/2020/11/19/new-u.s.-missile-defense-test-may-have-increased-risk-of-nuclear-war-pub-83273|title = A New U.S. Missile Defense Test May Have Increased the Risk of Nuclear War}}</ref> Under SDIO's Innovative Sciences and Technology Office,<ref>{{Cite news|url=http://tech.mit.edu/V105/N47/sdi.47n.html|title=SDIO Funds Research|date=November 5, 1985|work=MIT: The Tech|access-date=May 21, 2018|archive-date=August 8, 2012|archive-url=https://web.archive.org/web/20120808172209/http://tech.mit.edu/V105/N47/sdi.47n.html|url-status=dead}}</ref><ref>{{Cite news|title=Special-Presentation Innovative Science and Technology Programs|date=June 1988|work=SPIE|doi=10.1117/12.947548}}</ref><ref>{{Cite news|url=https://www.inc.com/magazine/19870401/3487.html|title=Star Wars' Inc.|date=April 1987|work=Inc Magazine}}</ref><ref>{{Cite journal|title=Washington Ins & Outs: Ionson and Mense Leave SDIO|date=June 1988|journal=Physics Today|doi=10.1063/1.2811448|last1=Goodwin |first1=Irwin |volume=41 |issue=6 |page=53 |bibcode=1988PhT....41f..53G }}</ref><ref>{{Cite news|url=https://www.the-scientist.com/?articles.view/articleNo/9425/title/Low-Profile-for-SDI-Work-on-Campus/|title=Low Profile for SDI Work on Campus|date=May 1988|work=The Scientist Magazine}}</ref><ref>{{Cite news|url=http://tech.mit.edu/V105/N46/sdi.46n.html|title=Ionson Counters SDI Dispute|date=November 1985|work=MIT: The Tech|access-date=May 21, 2018|archive-date=August 8, 2012|archive-url=https://web.archive.org/web/20120808200002/http://tech.mit.edu/V105/N46/sdi.46n.html|url-status=dead}}</ref><ref>{{Cite news|url=http://tech.mit.edu/V105/N45/sdi.45n.html|title=Ionson Defends SDI Program|date=October 1985|work=MIT: The Tech|access-date=May 21, 2018|archive-date=June 16, 2012|archive-url=https://web.archive.org/web/20120616203932/http://tech.mit.edu/V105/N45/sdi.45n.html|url-status=dead}}</ref> investment was made in [[basic research]] at national laboratories, universities, and in industry. These programs have continued to be key sources of funding for research scientists in [[particle physics]], supercomputing/[[computation]], advanced materials, and other critical science and engineering disciplines.

In 1987, the [[American Physical Society]] concluded that the technologies were decades away from readiness, and at least another decade of research was required to know whether such a system was even possible.<ref>{{cite journal|title=Report to The American Physical Society of the study group on science and technology of directed energy weapons|last1=APS Study Group Participants|first2=N.|last2=Bloembergen|first3=C. K. N.|last3=Patel|first4=P.|last4=Avizonis|first5=R. G.|last5=Clem|first6=A.|last6=Hertzberg|first7=T. H.|last7=Johnson|first8=T.|last8=Marshall|first9=R. B.|last9=Miller|first10=W. E.|last10=Morrow|first11=E. E.|last11=Salpeter|first12=A. M.|last12=Sessler|first13=J. D.|last13=Sullivan|first14=J. C.|last14=Wyant|first15=A.|last15=Yariv|first16=R. N.|last16=Zare|first17=A. J.|last17=Glass|first18=L. C.|last18=Hebel|last19=APS Council Review Committee|first20=G. E.|last20=Pake|first21=M. M.|last21=May|first22=W. K.|last22=Panofsky|first23=A. L.|last23=Schawlow|first24=C. H.|last24=Townes|first25=H.|last25=York|date=July 1, 1987|journal=Reviews of Modern Physics|volume=59|issue=3|pages=S1–S201|doi=10.1103/RevModPhys.59.S1|bibcode = 1987RvMP...59....1B|doi-access=free}}</ref> After the publication of the APS report, SDI's budget was cut. By the late 1980s, the effort had re-focused on the "[[Brilliant Pebbles]]" concept using small orbiting missiles, such as a lower cost conventional [[air-to-air missile]].

SDI was derisively nicknamed the [[Star Wars]] program, and criticized for threatening to destabilize the MAD-approach, and to re-ignite "an offensive [[arms race]]".<ref>{{Cite book |last=Nolan |first=Cathal J. |url={{google books|plainurl=yes|id=FMJ8KP8i3v0C|page=1600}}|page=1600|title=The Greenwood Encyclopedia of International Relations: S-Z |date=2002 |publisher=Greenwood Pub. |isbn=978-0-313-32383-6 |language=en}}</ref> In a 1986 speech, Senator [[Joe Biden]] claimed “'Star Wars' represents a fundamental assault on the concepts, alliances and arms-control agreements that have buttressed American security for several decades, and the president’s continued adherence to it constitutes one of the most reckless and irresponsible acts in the history of modern statecraft.”<ref>{{cite web|url=https://www.msn.com/en-us/news/world/opinion-ronald-reagan-just-saved-israel-from-iran-s-attack/ar-BB1lOirJ|title=Opinion: Ronald Reagan Just Saved Israel From Iran's Attack|work=[[MSN.com]]}}</ref>

Through declassified intelligence material, the wider implications and effects of the program revealed that due to the potential neutralization of its arsenal and resulting loss of a balancing power factor, SDI was a cause of grave concern for the Soviet Union and its successor state Russia.<ref>{{cite web|url=https://www.businessinsider.com/why-missile-defense-terrified-the-soviets-2014-10?r=DE&IR=T|title = A Newly Declassified CIA Paper Details a Tense Subplot in the Cold War Arms Race|website = [[Business Insider]]}}</ref> Following the [[Cold War]] when nuclear arsenals were shrinking, political support for SDI collapsed. SDI ended in 1993, when the [[Clinton Administration]] redirected the efforts towards [[theatre ballistic missile]]s and renamed the agency the [[Ballistic Missile Defense Organization]] (BMDO).

In 2019, elements, specifically the observation portions, of the program re-emerged with [[First presidency of Donald Trump|President Trump's]] signing of the [[National Defense Authorization Act]].<ref>{{cite web |url=https://www.armscontrol.org/act/2018-09/news/congress-calls-interceptors-space |title=Congress Calls for Interceptors in Space |first= Kingston |last= Reif |date=September 1, 2018}}</ref> The program is managed by the [[Space Development Agency]] (SDA) as part of the new National Defense Space Architecture (NDSA).<ref>{{cite web|author=Nathan Strout |title=What will the Space Development Agency really do?|url=https://www.sda.mil/what-will-the-space-development-agency-really-do/|date=24 July 2019}}</ref><ref>{{cite news |last=Erwin|first=Sandra|url=https://spacenews.com/spacex-l3harris-win-space-development-agency-contracts-to-build-missile-warning-satellites/|title=L3Harris, SpaceX win Space Development Agency contracts to build missile-warning satellites|newspaper=SpaceNews|date=5 October 2020|access-date=1 December 2021}}</ref> [[CIA]] Director [[Mike Pompeo]] called for additional funding to achieve a full-fledged "Strategic Defense Initiative for our time, the SDI II" though it is unclear what this had to do with SDA.<ref>{{cite web |url=https://nationalinterest.org/feature/nuclear-weapons-china-and-strategic-defense-initiative-century-199549 |title=Nuclear Weapons, China, and a Strategic Defense Initiative for this Century |first= Mike |last= Pompeo |date=January 18, 2022 }}</ref>

==History==
===National BMD===
The [[US Army]] considered the issue of ballistic missile defense (BMD) after [[World War II]]. Studies suggested that attacking a [[V-2 rocket]] would be difficult because the flight time was so short that it would leave little time to forward information through [[command and control]] networks to missile batteries. [[Bell Labs]] pointed out that although longer-range missiles flew much faster, their longer flight times would ease the timing issue and their high altitudes would ease long-range [[radar]] detection.{{sfn|Jayne|1969|p=29}}

This led to a series of projects including [[Nike Zeus]], [[Nike-X]], [[Sentinel program|Sentinel]] and ultimately the [[Safeguard Program]], all aimed at developing a system to defend against attacks by Soviet ICBMs. The programs proliferated because of the changing threat; the Soviets claimed to be producing missiles "like sausages", and ever-more missiles would be needed to defend against their fleet. Low-cost countermeasures such as [[penetration aids|radar decoys]] required additional interceptors. An early estimate suggested $20 spent on defense would be required for every $1 the Soviets spent on offense. The addition of [[Multiple independently targetable reentry vehicle|MIRV]] in the late 1960s further moved the balance in favor of offensive systems. This massively skewed [[cost-exchange ratio]] prompted observers to propose that an [[arms race]] was inevitable.{{sfn|Kent|2008|p=49}}

[[File:LIM-49A Spartan mockup.png|thumb|The [[Nike-X|Extended Range Nike Zeus]]/[[LIM-49A Spartan|Spartan missile]] of the late-1960s was designed to provide full-country defense as part of the Sentinel-[[Safeguard Program|Safeguard]] programs. Projected to cost $40&nbsp;billion (${{inflation|US|40|1966}} billion in {{currentyear}}) it would have offered minimal protection and damage prevention in an all-out attack.{{sfn|Ritter|2010|p=154}}]]

President Dwight D. Eisenhower asked [[DARPA|ARPA]] to consider alternative concepts. Their Project Defender studied many approaches before concentrating on [[Project BAMBI]]. BAMBI used satellites carrying interceptors that would attack the Soviet ICBMs upon launch. This [[boost phase]] intercept rendered MIRV impotent; a successful attack would destroy all of the warheads. Unfortunately, the operational cost of such a system was so large that the [[US Air Force]] rejected the concepts. Development was cancelled in 1963.<ref>{{cite web |website=Astronautix.com |url=http://www.astronautix.com/b/bambi.html |archive-url=https://web.archive.org/web/20161227220849/http://astronautix.com/b/bambi.html |url-status=dead |archive-date=December 27, 2016 |title=Bambi}}</ref><ref>{{cite news |url=https://www.nytimes.com/1986/10/28/science/star-wars-traced-to-eisenhower-era.html |newspaper=The New York Times |title='STAR WARS' Traced to Eisenhower Era |first= William |last= Broad |date=October 28, 1986}}</ref>

During this period, the entire topic of BMD became increasingly controversial. Early deployment plans were met with little interest, but by the late 1960s, public meetings on the Sentinel system were met by thousands of angry protesters.<ref name=today>{{cite web |first=Sharon |last=Watkins Lang |url=http://www.army.mil/article/142123/SMDC_History__Today_in_Space_and_Missile_Defense_History/ |title=Today in Space and Missile Defense History |date=February 3, 2015 |website=US Army}}</ref> After thirty years of effort, only one such system was built; a single base of the original Safeguard system became operational in April 1975, but was closed in February 1976.<ref>{{cite news
|title=Safeguard ABM System to Shut Down
|newspaper=The New York Times
|date=November 25, 1975
|author=John W. Finney
|url=https://www.nytimes.com/1975/11/25/archives/safeguard-abm-system-to-shut-down-5-billion-spent-in-6-years-since.html
|quote=the utility of Safeguard to protect Minuteman will be essentially nullified in the future}}</ref>

A Soviet military [[A-35 anti-ballistic missile system]] was deployed around Moscow to intercept enemy [[ballistic missile]]s targeting the city or its surrounding areas. The A-35 was the only Soviet ABM system allowed under the 1972 [[Anti-Ballistic Missile Treaty]]. In development since the 1960s and in operation from 1971<ref name=astro>{{cite encyclopedia |url=http://www.astronautix.com/lvs/a35.htm |title=A35 |encyclopedia=Encyclopedia Astronautica |access-date=June 7, 2007 |archive-url=https://web.archive.org/web/20070702003434/http://www.astronautix.com/lvs/a35.htm |archive-date=July 2, 2007 |url-status=dead }}</ref> until the 1990s, it featured the nuclear-tipped [[ABM-1 Galosh|A350]] [[exoatmospheric]] interceptor missile.

===Lead up to SDI===
{{main|X-ray laser}}

[[Image:Tumbler_Snapper_rope_tricks.jpg|thumb|upright=1.0|The bright spikes extending below the initial fireball of one of 1952's [[Operation Tumbler–Snapper]] test shots, are known as the "[[rope trick effect]]". They are caused by the intense flash of ''thermal''/[[soft X-rays]] released by the explosion heating the steel tower guy-wires white hot. The development of the [[W71]] and the [[Project Excalibur]] x-ray laser were based on enhancing the destructive effects of these x-rays.]]

[[George Shultz]], Reagan's [[Secretary of State of the United States|secretary of state]], suggested that a 1967 lecture by physicist [[Edward Teller]] was an important precursor to SDI. In the lecture, Teller talked about the idea of defending against nuclear missiles using [[nuclear weapon]]s, principally the [[W65 (nuclear warhead)|W65]] and [[W71]], with the latter an enhanced thermal/X-ray device used on the [[LIM-49 Spartan|Spartan missile]] in 1975. Held at [[Lawrence Livermore National Laboratory]] (LLNL), the 1967 lecture was attended by Reagan shortly after he became governor of California.<ref name=gps>{{Cite book |last=Shultz |first=George Pratt |authorlink=George P. Shultz |url={{google books|plainurl=yes|id=96LVnQEACAAJ|page=261}} |page=261|title=Turmoil and Triumph: My Years as Secretary of State |date=1993 |publisher=Scribner's |isbn=978-0-684-80332-6 |language=en}}</ref>

Development of [[laser weapon]]s in the [[Soviet Union]] began in 1964–1965.<ref>{{cite web|url=http://www.fas.org/spp/starwars/program/soviet/990600-bmd-rus.htm|work=[[Nevsky Bastion]]|publisher=Federation of American Scientists|author=A. Karpenko|title=ABM And Space Defense|year=1999|pages=2–47}}</ref> Though classified at the time, a detailed study on a Soviet space-based laser system began no later than 1976 with the [[Polyus (spacecraft)|Polyus]], a 1 MW [[Carbon dioxide laser]]-based orbital weapons platform prototype. Development was also started on the anti-satellite ''Kaskad'' in-orbit missile platform.<ref>{{cite web|url=http://www.thespacereview.com/article/2394/2|title=The Space Review: Plagiarism in several space history articles (page 2)|date=October 8, 2017|archive-url=https://web.archive.org/web/20171008102950/http://www.thespacereview.com/article/2394/2|archive-date=October 8, 2017}}</ref><ref name="web.archive.org">{{cite web|url=http://arstechnica.com/science/2013/05/the-soviet-response-to-star-wars-that-never-was/2/|title=The secret laser-toting Soviet satellite that almost was – Ars Technica|date=September 26, 2013|archive-url=https://web.archive.org/web/20130926143351/http://arstechnica.com/science/2013/05/the-soviet-response-to-star-wars-that-never-was/2/|archive-date=September 26, 2013}}</ref>

A [[revolver cannon]] ([[Rikhter R-23]]) was mounted on the 1974 Soviet [[Salyut 3]] space station, a satellite that successfully test-fired its cannon in orbit.<ref name=Olberg>{{cite web| url = http://space.au.af.mil/books/oberg/ch02.pdf| title = James Olberg, ''Space Power Theory'', Ch. 2| access-date = June 17, 2013| archive-date = July 12, 2018| archive-url = https://web.archive.org/web/20180712205157/http://space.au.af.mil/books/oberg/ch02.pdf| url-status = dead}}</ref><ref>{{cite web|url=http://www.popularmechanics.com/military/weapons/a18187/here-is-the-soviet-unions-secret-space-cannon/|title=Here Is the Soviet Union's Secret Space Cannon|date=November 16, 2015}}</ref>

In 1979, Teller contributed to a [[Hoover Institution]] publication where he claimed that the US would be facing an emboldened USSR due to their work on [[civil defense]]. Two years later at a conference in Italy, he made the same claims about their ambitions, now emboldened by new space-based weapons. According to popular opinion, shared by author [[Frances FitzGerald (journalist)|Frances FitzGerald]], no evidence validated that such research was carried out. Instead, Teller was promoting his latest weapon, the [[X-ray laser]] that was finding only limited funding, his speech in Italy was a new attempt to synthsize a [[missile gap]].<ref>{{Cite book |last=FitzGerald |first=Frances |url={{google books|plainurl=yes|id=nv2v0fCAONwC|page=128}} |title=Way Out There In the Blue: Reagan, Star Wars and the End of the Cold War |date=2001-02-21 |publisher=Simon and Schuster |isbn=978-0-7432-0377-7 |pages=128 |language=en}}</ref>

In 1979, Reagan visited the [[NORAD]] command base, [[Cheyenne Mountain Complex]], where he was introduced to the extensive tracking and detection systems extending throughout the world and into space; however, he was struck by their comments that while they could track the attack down to the individual targets, they could not stop it. Reagan felt that in the event of an attack, this would place the president in a terrible position, having to choose between immediate counterattack or absorbing the attack while maintaining offensive dominance. Shultz suggested that this feeling of helplessness, coupled with Teller's defensive ideas combined to motivate SDI.<ref name=gps/>{{rp|261–62}}

In the fall of 1979, at Reagan's request, Lieutenant General [[Daniel O. Graham]], the former head of the [[Defense Intelligence Agency|DIA]], briefed Reagan on an updated BAMBI he called High Frontier, a missile shield composed of multi-layered ground- and space-based weapons that could track, intercept, and destroy ballistic missiles, theoretically enabled by emerging technologies. It was designed to replace the [[mutual assured destruction|MAD]] doctrine.<ref>{{cite book|first=Daniel O. |last=Graham|authorlink=Daniel O. Graham |url=http://www.danielgraham.net/content/Chapter14.htm |title=Confessions of a Cold Warrior: An Autobiography|archive-url=https://web.archive.org/web/20070311033905/http://www.danielgraham.net/content/Chapter14.htm |archive-date=March 11, 2007 |publisher= Preview Press|year=1995|isbn=0-9644495-2-8}}</ref> In September 1981, Graham formed a small, Virginia-based [[think tank]] called High Frontier to continue research on the missile shield. [[The Heritage Foundation]] provided High Frontier with research space, and Graham published a 1982 report entitled, "High Frontier: A New National Strategy" that examined in greater detail how the system would function.<ref>{{Cite book |url=http://dx.doi.org/10.1093/acref/9780199759255.001.0001 |title=The Oxford Encyclopedia of American Military and Diplomatic History |date=2013-01-01 |publisher=Oxford University Press |isbn=978-0-19-975925-5 |editor-last=Lynch |editor-first=Timothy J. |volume=2 |pages=360 |chapter=Think Tanks and US Military and Diplomatic Affairs|doi=10.1093/acref/9780199759255.001.0001 }}</ref>

Since the late 1970s, another group had been pushing for the development of a high-powered orbital chemical laser  attack ICBMs, the Space Based Laser (SBL). New developments under [[Project Excalibur]] by Teller's "O-Group" at [[Lawrence Livermore National Laboratory]](LLNL) suggested that a single [[X-ray laser]] could shoot down dozens of missiles with a single shot.<ref>{{cite news | title = 'Cold Fusion' Patents Sought | first = Broad | last = William J. | date = April 13, 1989 |work=The New York Times | url = https://www.nytimes.com/1989/04/13/us/cold-fusion-patents-sought.html }}</ref> The groups began to meet in order to prepare their plans for the incoming president.

The group met with Reagan several times during 1981 and 1982, apparently with little effect, while the buildup of new offensive weaponry like the [[B-1 Lancer]] and [[MX missile]] continued. However, in early 1983, the [[Joint Chiefs of Staff]] met with the president and outlined the reasons why they might consider shifting some of the funding from the offensive side to new defensive systems.

According to a 1983 US Interagency Intelligence Assessment, good evidence indicated that in the late 1960s the Soviets were devoting serious thought to both explosive and non-explosive nuclear power sources for lasers.<ref>{{cite web|url=https://fas.org/spp/starwars/offdocs/m8310017.htm|title=Possible Soviet Responses to the US Strategic Defense Initiative Interagency Intelligence Assessment.1983. "There is good evidence that in the late 1960s the Soviets were giving serious thought to both explosive and nonexplosive nuclear power sources for lasers of an unknown type."|access-date=April 4, 2015|archive-date=May 7, 2015|archive-url=https://web.archive.org/web/20150507003220/http://fas.org/spp/starwars/offdocs/m8310017.htm|url-status=dead}}</ref>

==Project and proposals==
[[File:Reagan SDI Speech 1983.ogv|thumb|right|President Reagan delivering the March 23, 1983, speech initiating SDI]]

=== Announcement ===
On March 23, 1983, Reagan announced SDI in a nationally televised speech, stating "I call upon the scientific community in this country, those who gave us nuclear weapons, to turn their great talents to the cause of mankind and world peace, to give us the means of rendering these nuclear weapons impotent and obsolete."<ref>{{cite web| url = https://www.reaganlibrary.gov/archives/speech/address-nation-defense-and-national-security| title = "Address to the Nation on Defense and National Security", March 23, 1983}}</ref>

=== Strategic Defense Initiative Organization (SDIO) ===
In 1984, the Strategic Defense Initiative Organization (SDIO) was established to oversee the program, which was headed by Lt. General [[James Alan Abrahamson]] USAF, a past Director of the [[Space Shuttle program]].<ref name="fas_milestones" />

In addition to original Heritage ideas, other concepts were considered. Notable among these were [[particle-beam weapon]]s, updated versions of [[nuclear shaped charge]]s, and various [[Directed-energy weapon|plasma weapons]]. SDIO invested in computer systems, component miniaturization, and sensors.

Initially, the program focused on large-scale systems designed to defeat a massive Soviet offensive strike. For this mission, SDIO concentrated almost entirely on "high tech" solutions like lasers. Graham's proposal was repeatedly rejected by members of the Heritage group as well as within SDIO; when asked about it in 1985, Abrahamson suggested that the concept was underdeveloped and was not considered.

By 1986, many of the promising ideas were failing. Teller's X-ray laser, run under [[Project Excalibur]], failed several key tests in 1986 and was targeted to the anti-satellite role. The particle beam concept was demonstrated to basically not work, as was the case with several other concepts. Only the Space-Based Laser seemed to have any hope of developing in the short term, but it was growing in size due to its fuel consumption.

=== APS report ===
The [[American Physical Society]] (APS) had been asked by SDIO to provide a review of the various concepts. They put together an all-star panel including many of the inventors of the laser, including a [[Nobel laureate]]. Their initial report was presented in 1986, but was released to the public (in redacted form) in early 1987.<ref name=APS>{{cite tech report |url=http://digitalcollections.library.cmu.edu/awweb/awarchive?type=file&item=710809 |title=The Science and Technology of Directed Energy Weapons |publisher=APS |date=April 1986}}</ref>

The report considered all of the systems then under development and concluded none of them were anywhere near ready for deployment. Specifically, they noted that all of the systems had to improve their energy output by at least 100 times, and in some cases by as much as a million. In other cases, like Excalibur, they dismissed the concept entirely. Their summary stated simply:

<blockquote>We estimate that all existing candidates for directed energy weapons (DEWs) require two or more orders of magnitude, (powers of 10) improvements in power output and beam quality before they may be seriously considered for application in ballistic missile defense systems.<ref name=APS/></blockquote>

They concluded that none of the systems could be deployed as an anti-missile system until the next century.<ref name=APS/>

===Strategic Defense System===
Faced with this report and accompanying negative press, SDIO changed direction. Beginning in late 1986, Abrahamson proposed that SDI would be based on the system he had previously dismissed, a version of High Frontier now named the "Strategic Defense System, Phase I Architecture". The name implied that the concept would be replaced by more advanced systems in future phases.

Strategic Defense System (SDS) was the low-earth orbit (LEO) [[Smart Rocks]] concept with an added layer of ground-based missiles sited in the US. These missiles were intended to attack warheads that the Smart Rocks missed. In order to track them below the [[radar horizon]], SDS added more LEO satellites that would feed tracking information to both the space-based "garages" as well as the ground-based missiles.<ref>{{Cite web |access-date=2024-07-05 |website=U.S. Department of Defense |language=en-US|author=Missile Defense Agency |authorlink=Missile Defense Agency |url=http://www.defenselink.mil/specials/missiledefense/history.html |title=History of the Missile Defense Organization}}</ref> Later [[Ground-Based Midcourse Defense|ground-based systems]] trace derived from this concept.

LLNL then introduced the [[Brilliant Pebbles]] concept. This was essentially the combination of the sensors on the garage satellites and the tracking stations. Advancements in sensors and [[microprocessors]] allowed this to be packaged in a small missile nose cone. Subsequent studies suggested that this approach would be cheaper, easier to launch and more resistant to counterattack, and in 1990 Brilliant Pebbles was selected as the baseline model for SDS Phase 1.

=== Global Protection Against Limited Strikes ===
While SDIO pursued SDS, the [[Warsaw Pact]] was rapidly disintegrating, culminating in the destruction of the [[Berlin Wall]] in 1989. One of the many reports on SDS considered these events and suggested that a massive defense against a Soviet launch would become unnecessary. However, short and medium range missile technology would likely proliferate as the Soviet Union disintegrated and sold off its hardware. One of the core ideas behind Global Protection Against Limited Strikes (GPALS) was that the Soviet Union would not always be the aggressor and the United States would not always be the target.<ref name=":0" />

Instead of a heavy defense aimed at ICBMs, this report suggested realigning GPALS deployment. Against novel threats the [[Brilliant Pebbles]] would have limited utility, largely because the missiles fired for only a short period and the warheads did not rise high enough for them to be easily tracked by a satellite above them. GPALS thus added a mobile ground-based missile and more low-orbit satellites known as [[Brilliant Eyes]] to feed the Pebbles.

GPALS was approved by [[George H. W. Bush|President George H.W. Bush]] in 1991.<ref name=":0">{{Cite book|title=The Militarization and Weaponization of Space (1st ed.)|last=Mowthorpe|first=Matthew|publisher=Lexington Books|year=2004|location=New York}}</ref> The system would cut the proposed costs of the SDI system from $53&nbsp;billion to $41&nbsp;billion over a decade.<ref name=":0" /> Instead of attempting to protect against thousands of incoming missiles, GPALS sought to provide protection from up to two hundred nuclear missiles.<ref name=":1">{{Cite magazine|last=Morrison|first=David|year=1992|title=Starburst|magazine=The New Republic|volume=206|pages=21–23}}</ref> GPALS was tasked to protect the United States from attacks coming from all different parts of the world.<ref name=":1" />

=== Ballistic Missile Defense Organization (BMDO) ===
In 1993, the [[Bill Clinton|Clinton]] administration further shifted the focus to ground-based interceptor missiles and theater-scale systems, forming the [[Ballistic Missile Defense Organization]] (BMDO) and closing BMDO was renamed by the [[George W. Bush]] administration as the [[Missile Defense Agency]] and focused on limited [[United States national missile defense|National Missile Defense]].

==Ground-based programs==
[[File:ERINT.jpg|left|thumb|upright|Extended Range Interceptor (ERINT) launch from White Sands Missile Range]]

===Extended Range Interceptor (ERINT)===
The Extended Range Interceptor (ERINT) program was part of SDI's Theater Missile Defense Program and was an extension of the Flexible Lightweight Agile Guided Experiment (FLAGE), which included developing hit-to-kill technology and demonstrating the guidance accuracy of a small, agile, radar-homing vehicle.

FLAGE scored a direct hit against a [[MGM-52 Lance]] missile in flight, at [[White Sands Missile Range]] in 1987. ERINT was a prototype missile similar to the FLAGE, but it used a new solid-propellant rocket motor that allowed it to fly faster and higher than FLAGE.

ERINT was later chosen as the [[MIM-104 Patriot]] (Patriot Advanced Capability-3, PAC-3) missile.<ref>{{cite web|author=White Sands Missile Range|authorlink=White Sands Missile Range|url=http://www.wsmr.army.mil/pao/HistoricPhotos/PAGES/ERINT.htm |title=ERINT – Extended Range Interceptor|archive-url=https://web.archive.org/web/20060623163359/http://www.wsmr.army.mil/pao/HistoricPhotos/PAGES/ERINT.htm |archive-date=June 23, 2006 |access-date=March 10, 2006}}</ref>

===Homing Overlay Experiment (HOE)===
[[File:ABM test vehicle (Homing Overlay Experiment).jpg|thumb|right|{{cvt|13|ft|m|0}} diameter web deployed by Homing Overlay Experiment]]
Given concerns about previous programs' nuclear-tipped interceptors, in the 1980s the US Army began studies about the feasibility of kinetic hit-to-kill vehicles, i.e. interceptors that would destroy incoming ballistic missiles by colliding with them.

The Homing Overlay Experiment (HOE) was the first such system tested by the Army, and the first successful hit-to-kill intercept of a mock ballistic missile warhead outside the Earth's atmosphere.<ref>{{cite web| url = https://www.lockheedmartin.com/en-us/news/features/history/hoe.html| title = Striking a Bullet with a Bullet: HOE|author= Lockheed Martin Corporation| date = March 28, 2022}}</ref>

HOE used a [[kinetic kill vehicle]] (KKV). The KKV was equipped with an infrared seeker, guidance electronics and a propulsion system. Once in space, the KKV could extend a folded structure similar to an umbrella skeleton of {{cvt|4|m|ft|order=flip}} diameter to enhance its effective cross section. This device was intended to destroy an ICBM reentry vehicle on collision.

Four test launches were conducted in 1983 and 1984 at [[Kwajalein Missile Range]] in the [[Marshall Islands]] using first two stages of [[Minuteman missile]], M55E1 and M56A1.<ref>{{Cite web |title=HOE |url=https://space.skyrocket.de/doc_lau/hoe.htm |access-date=2024-12-06 |website=Gunter's Space Page |language=en}}</ref> For each test a Minuteman missile was launched from [[Vandenberg Air Force Base]] in California carrying a single mock re-entry vehicle targeted for Kwajalein lagoon more than {{convert|4000|mi|km}} away.<ref>{{cite web| url = http://www.designation-systems.net/dusrm/app4/hoe.html| title = Directory of U.S. Military Rockets and Missiles * Appendix 4: Undesignated Vehicles * HOE; Andreas Parsch, 2003.}}</ref>

After test failures with the first three flight tests because of guidance and sensor problems, the DOD reported that the fourth and final test on June 10, 1984, was successful, intercepting the Minuteman RV with a closing speed of about {{cvt|6.1|km/s|mi/s|order=flip}} at an altitude of more than {{cvt|100|mi}}.<ref>{{cite encyclopedia|encyclopedia=Encyclopedia Astronautica   |title=Index: 1 |url=http://www.astronautix.com/4/404page.html |access-date=2024-07-05}}</ref>

Although the fourth test was described as a success, the ''New York Times'' in August 1993 reported that the HOE4 test was rigged to increase the likelihood of success.<ref>{{cite news|last1=Weiner|first1=Tim|title=Lies and Rigged 'Star Wars' Test Fooled the Kremlin, and Congress|url=https://www.nytimes.com/1993/08/18/us/lies-and-rigged-star-wars-test-fooled-the-kremlin-and-congress.html|access-date=December 22, 2015|newspaper=The New York Times|date=August 18, 1993}}</ref> At the urging of Senator [[David Pryor]], the [[General Accounting Office]] investigated the claims and concluded that though steps were taken to make it easier for the interceptor to find its target (including some of those alleged by the ''New York Times''), the available data indicated that the interceptor had been successfully guided by its onboard infrared sensors in the collision, and not by an onboard radar guidance system as alleged.<ref>{{cite web| url = http://archive.gao.gov/t2pbat2/152203.pdf| title = United States General Accounting Office, Ballistic Missile Defense: ''Records Indicate Deception Program Did Not Affect 1984 Test Results,'' GAO/NSIAD-94-219; Secretary of Defense Les Aspin, Press Briefing, September 9, 1993.}}</ref> Per the GAO report, the net effect of the DOD enhancements increased the infrared signature of the target vessel by 110% over the realistic missile signature initially proposed for the HOE program, but nonetheless the GAO concluded the enhancements to the target vessel were reasonable given the objectives of the program and the geopolitical consequences of its failure. Further, the report concluded that the DOD's subsequent statements before Congress about the HOE program "fairly characterize[d]" the success of HOE4, but confirmed that the DOD never disclosed to Congress the enhancements made to the target vessel.

HOE technology was later expanded into the Exoatmospheric Reentry-vehicle Interception System program.<ref>{{cite encyclopedia|encyclopedia=Encyclopedia Astronautica |url=http://www.astronautix.com/lvs/hoe.htm |title=SVC Lockheed HOE|archive-url=https://web.archive.org/web/20031026093929/http://astronautix.com/lvs/hoe.htm |archive-date=October 26, 2003 |access-date=March 10, 2006}}</ref>

===ERIS and HEDI===
{{Main|Exoatmospheric Reentry-vehicle Interceptor Subsystem|High Endoatmospheric Defense Interceptor}}

Developed by [[Lockheed Corporation|Lockheed]] as part of the ground-based interceptor portion of SDI, the [[Exoatmospheric Reentry-vehicle Interceptor Subsystem|Exoatmospheric Reentry-vehicle Interceptor Subsystem (ERIS)]] began in 1985, with at least two tests occurring in the early 1990s. This system was never deployed, but its technology was used in the [[Terminal High Altitude Area Defense]] (THAAD) system and the [[Ground-Based Interceptor]] currently deployed as part of the [[Ground-Based Midcourse Defense]] (GMD) system.<ref>{{cite encyclopedia|encyclopedia=Encyclopedia Astronautica |url=http://astronautix.com/lvs/eris.htm |title=Lockheed ERIS|archive-url=https://web.archive.org/web/20020501080925/http://www.astronautix.com/lvs/eris.htm |archive-date=May 1, 2002 |access-date=March 10, 2006}}</ref>

==Directed-energy weapon (DEW) programs==
{{See also|Directed-energy weapon}}

===X-ray laser===
[[File:Space Laser Satellite Defense System Concept.jpg|thumb|The 1984 SDI concept of a space based [[Nuclear pumped laser|Nuclear ''reactor'' pumped laser]] or a chemical [[hydrogen fluoride laser]] satellite<ref>{{Cite web|url=https://www.fas.org/spp/starwars/program/sbl.htm|title=Space Based Laser. FAS.}}</ref> resulted in this 1984 artist's concept of a laser-equipped satellite firing on another, causing a momentum change in the target object by [[laser ablation]]. Before having to cool and re-aim at further possible targets.]]

{{main|Project Excalibur}}
[[File:Excalibur firing.png|thumb|This early artwork of the [[Project Excalibur|Nuclear ''detonation'' pumped laser array]] depicts an [[Project Excalibur|Excalibur engaging]] three targets, simultaneously. In most descriptions, each Excalibur could fire at dozens of targets, which would be hundreds or thousands of miles away.]]
An early SDI focus was an [[X-ray]] [[laser]] powered by [[nuclear explosion]]s. Nuclear explosions give off a burst of X-rays, which the Excalibur concept intended to focus using a [[lasing medium]] consisting of metal rods. Many such rods would be placed around a warhead, each aimed at a different ICBM, thus destroying many ICBMs in a single attack. It would cost much less for the US to build another Excalibur than the Soviets would need to build enough new ICBMs to counter it. The idea was first based on satellites, but when it was pointed out that these could be attacked in space, the concept moved to a "pop-up" concept, with the device launched from a submarine off the northern Soviet coast.

However, on March 26, 1983,<ref>{{cite web|publisher=[[United States Department of Energy]] |url=http://www.nv.doe.gov/library/publications/historical/DOENV_209_REV15.pdf |title=United States Nuclear Tests 1945–1992 |archive-url=https://web.archive.org/web/20061012160826/http://www.nv.doe.gov/library/publications/historical/DOENV_209_REV15.pdf |archive-date=October 12, 2006 |access-date=March 10, 2006}}</ref> the first test (known as the [[Operation Phalanx|Cabra event]]), was performed in an underground shaft and resulted in marginally positive readings possibly caused by a faulty detector. Since a nuclear explosion was used as the power source, the detector was destroyed during the experiment, and the results therefore could not be confirmed. Technical criticism<ref>{{cite journal | last1=Bloembergen | first1=N. | last2=Patel | first2=C. K. N. | last3=Avizonis | first3=P. | last4=Clem | first4=R. G. | last5=Hertzberg | first5=A. | last6=Johnson | first6=T. H. | last7=Marshall | first7=T. | last8=Miller | first8=R. B. | last9=Morrow | first9=W. E. | last10=Salpeter | first10=E. E. | last11=Sessler | first11=A. M. | last12=Sullivan | first12=J. D. | last13=Wyant | first13=J. C. | last14=Yariv | first14=A. | last15=Zare | first15=R. N. | last16=Glass | first16=A. J. | last17=Hebel | first17=L. C. | last18=Pake | first18=G. E. | last19=May | first19=M. M. | last20=Panofsky | first20=W. K. | last21=Schawlow | first21=A. L. | last22=Townes | first22=C. H. | last23=York | first23=H. |display-authors=5| title=Report to The American Physical Society of the study group on science and technology of directed energy weapons | journal=Reviews of Modern Physics | publisher=American Physical Society (APS) | volume=59 | issue=3 | date=1987-07-01 | issn=0034-6861 | doi=10.1103/revmodphys.59.s1 | pages=S1–S201| bibcode=1987RvMP...59....1B |doi-access=free}}</ref> based upon unclassified calculations suggested that the X-ray laser would be of at best marginal use.<ref>{{Citation |last=Tsipis |first=Kosta |title=Third-generation Nuclear Weapons |date=1989 |work=Military Technology, Armaments Dynamics and Disarmament |pages=67–91 |url=http://dx.doi.org/10.1007/978-1-349-10221-1_3 |access-date=2024-07-05 |place=London |publisher=Palgrave Macmillan UK |doi=10.1007/978-1-349-10221-1_3 |isbn=978-1-349-10223-5}}</ref> Critics often cite the X-ray laser system as SDI's primary focus, with its apparent failure warranting opposition to the program.

Despite the apparent failure, the legacy of the X-ray laser program is the knowledge gained from the research. A parallel development program advanced laboratory X-ray lasers<ref>{{Cite journal |last1=Rosen |first1=M. D. |last2=Hagelstein |first2=P. L. |last3=Matthews |first3=D. L. |last4=Campbell |first4=E. M. |last5=Hazi |first5=A. U. |last6=Whitten |first6=B. L. |last7=MacGowan |first7=B. |last8=Turner |first8=R. E. |last9=Lee |first9=R. W. |last10=Charatis |first10=G. |last11=Busch |first11=Gar. E. |last12=Shepard |first12=C. L. |last13=Rockett |first13=P. D. |date=1985-01-14 |title=Exploding-Foil Technique for Achieving a Soft X-Ray Laser |url=http://dx.doi.org/10.1103/physrevlett.54.106 |journal=Physical Review Letters |volume=54 |issue=2 |pages=106–109 |doi=10.1103/physrevlett.54.106 |pmid=10031256 |bibcode=1985PhRvL..54..106R |issn=0031-9007}}</ref> for biological imaging such as 3D [[holograms]] of living organisms. Other spin-offs include research on advanced materials like [[SEAgel]] and [[Aerogel]], the Electron-Beam Ion Trap facility for physics research, and techniques for early detection of breast cancer.<ref>{{cite web|author=Lawrence Livermore National Laboratory|url=http://www.llnl.gov/etr/pdfs/11_94.2.pdf |title=Legacy of the X-Ray Laser Program |date=November 1994|access-date=April 29, 2006}}</ref>

===Chemical laser===
[[File:Slbd front.jpg|thumb|right|SeaLite Beam Director, commonly used as the output for the MIRACL]]
{{See also|Chemical laser}}
Beginning in 1985, the [[United States Air Force|Air Force]] tested an SDIO-funded [[Hydrogen fluoride laser|deuterium fluoride laser]] known as [[MIRACL|Mid-Infrared Advanced Chemical Laser]] (MIRACL) at [[White Sands Missile Range]].<ref>{{cite web|title=SDI: Technology, Survivability, and Software|date=May 1988 |url=https://www.princeton.edu/~ota/disk2/1988/8837/8837.PDF|publisher=U.S. Government Printing Office|access-date=November 20, 2022}}</ref> During a simulation, the laser successfully destroyed a Titan missile booster in 1985. However, the test setup had the booster shell pressurized and under considerable compression loads. These test conditions were used to simulate the loads a booster would be under during launch.<ref>{{cite web|url=http://www.mda.mil/mdaLink/html/milstone.html |title=The Missile Defense Agency |archive-url=https://web.archive.org/web/20081224034505/http://www.mda.mil/mdaLink/html/milstone.html |archive-date=December 24, 2008 |author=U.S. Department of Defense}}</ref> The system was later tested for the US Navy on target drones simulating cruise missiles, with some success. After SDIO closed, MIRACL was tested on an old Air Force satellite for potential use as an [[anti-satellite weapon]], with mixed results. The technology was also used to develop the [[Tactical High Energy Laser]] (THEL) that was tested against in-flight artillery shells.<ref>{{cite web|author=Federation of American Scientists|url=https://fas.org/spp/military/program/asat/miracl.htm |title=Mid-Infrared Advanced Chemical Laser|archive-url=https://web.archive.org/web/20150409030521/https://fas.org/spp/military/program/asat/miracl.htm |archive-date=April 9, 2015 |access-date= April 8, 2006}}</ref>

During the mid-to-late 1980s panel discussions took place at various [[The International Conference on Lasers and Applications, Lasers 'XX|laser conferences]]. Proceedings include papers on the status of chemical and other high-power lasers.<ref name="Lasers87" />

The [[Missile Defense Agency]]'s [[Boeing YAL-1|Airborne Laser]] program used a chemical laser that intercepted a missile taking off, so an offshoot of SDI could be said to have successfully implemented one of the key goals of the program.<ref>{{Cite web |access-date=2024-07-05 |language=vi|url=http://www.globalsecuritynewswire.org/gsn/nw_20090609_8318.php |title=Airborne Laser Undergoes Successful Test |archive-url=https://web.archive.org/web/20090624170838/http://www.globalsecuritynewswire.org/gsn/nw_20090609_8318.php|archive-date=June 24, 2009|date=June 9, 2009|publisher= NTI: Global Security Newswire}}</ref>

===Neutral particle beam===
In July 1989, the Beam Experiments Aboard a Rocket (BEAR) program launched a sounding rocket containing a neutral [[particle beam]] (NPB) accelerator.<ref>{{cite web | url=https://apps.dtic.mil/sti/citations/ADA338597 | title=BEAR (Beam Experiments Aboard a Rocket) Project. Volume 1: Project Summary | date=January 1990 | last1=Nunz | first1=G. J. }}</ref> The experiment successfully demonstrated that a particle beam would operate and propagate as predicted outside the atmosphere and that no unexpected side-effects emerged when firing the beam in space. After the rocket was recovered, the particle beam was still operational. According to BMDO, the research on neutral particle beam accelerators, originally funded by SDIO, could eventually be used to reduce the [[half-life]] of nuclear waste products using [[Subcritical reactor|accelerator-driven transmutation technology]].<ref>{{cite web | url=https://world-nuclear.org/information-library/current-and-future-generation/accelerator-driven-nuclear-energy.aspx | title=Accelerator-driven Nuclear Energy &#124; Accelerator Driven Systems &#124; Transmutation - World Nuclear Association }}</ref>

===Laser and mirror experiments===
[[File:SDIO LACE Spacecraft.jpg|thumb|upright|Technicians at the Naval Research Laboratory (NRL) work on the [[Low-Power Atmospheric Compensation Experiment]] (LACE) satellite.]]
The High Precision Tracking Experiment (HPTE), launched with the [[Space Shuttle Discovery]] on [[STS-51-G]], was tested on June 21, 1985, when a Hawaii-based low-power laser successfully tracked the experiment and bounced the laser off of the HPTE mirror.

The Relay mirror experiment (RME), launched in February 1990, demonstrated critical technologies for space-based relay mirrors that would be used with an SDI [[directed-energy weapon]] system. The experiment validated stabilization, tracking, and pointing concepts and proved that a laser could be relayed from the ground to a {{cvt|60|cm|in|order=flip}} mirror on an orbiting satellite and back to another ground station with a high degree of accuracy and for extended durations.<ref>{{cite web|first=Malcolm R. |last=O'Neill|url=http://www.mda.mil/mdalink/html/oneilltest.html |title=Statement of Lieutenant General Malcolm R. O'Neill, USA, Director, BMDO before the Committee on National Security, House of Representatives |date=April 4, 1995|archive-url=https://web.archive.org/web/20060113224616/http://www.mda.mil/mdalink/html/oneilltest.html |archive-date=January 13, 2006 |access-date=March 11, 2006}}</ref>

Launched on the same rocket as the RME, the Low-power Atmospheric Compensation Experiment (LACE) satellite was built by the [[United States Naval Research Laboratory]] (NRL) to explore atmospheric distortion of lasers and real-time adaptive compensation. The LACE satellite included several other experiments to help develop and improve SDI sensors, including target discrimination using background radiation and tracking ballistic missiles using [[Ultraviolet]] Plume Imaging (UVPI).<ref>{{cite encyclopedia|encyclopedia=Encyclopedia Astronautica |access-date=2024-07-05 |url=http://www.astronautix.com/craft/lace.htm |title=Low-power Atmospheric Compensation Experiment (LACE) |archive-url=https://web.archive.org/web/20090721031741/http://www.astronautix.com/craft/lace.htm |archive-date=July 21, 2009 }}</ref> LACE was also used to evaluate ground-based [[adaptive optics]], a technique now used in civilian telescopes to remove atmospheric distortions.

===Hypervelocity Railgun (CHECMATE)===
Research on [[hypervelocity]] [[railgun]] technology was conducted to build an information base about railguns. The SDI railgun investigation, called the Compact High Energy Capacitor Module Advanced Technology Experiment, was able to fire two projectiles per day during the initiative. This represented a significant improvement over previous efforts, which were only able to achieve about one shot per month. Hypervelocity railguns are, at least conceptually, an attractive alternative to a space-based defense system because of their envisioned ability to quickly shoot at many targets. Also, since only the projectile leaves the gun, a railgun system can potentially fire many times before needing to be resupplied.

A hypervelocity railgun works like a [[particle accelerator]], converting [[electrical potential energy]] into [[kinetic energy]] for the projectile. A [[conductive]] pellet (the projectile) is attracted down the rails by [[electric current]] flowing through a rail. Through [[magnetic force]]s, a force is exerted on the projectile moving it down the rail. Railguns can generate muzzle-velocities in excess of {{convert|2.4|km/s|mi/s|order=flip}}.<ref>{{Cite news |work=Technology Review |url=http://www.technologyreview.com/Infotech/20164/?nlid=857 |title=Electromagnetic Railgun Blasts Off |date=February 6, 2008 |author=Brendan Borrell}}</ref>

Railguns face a host of technical challenges to be ready for battlefield deployment. First, the rails guiding the projectile must carry sufficient power. Each firing of the railgun sends tremendous current flow (almost half a million [[ampere]]s) through the rails, causing rapid erosion of the rail's surfaces (through [[ohmic heating]]), and even vaporization of the rail surface. Early prototypes were essentially single-use weapons, requiring complete rail replacement rails after each firing. Another challenge is projectile survivability. The projectiles experience acceleration force in excess of 100,000&nbsp;[[g-force|g]]. To be effective, the fired projectile must first survive the mechanical stress of firing and the thermal effects of a trip through the atmosphere at many times the speed of sound hitting its target. Any on-board guidance would require the onboard navigation system to be built to the same level of sturdiness as the main mass of the projectile.

In addition to destroying ballistic missile threats, railguns were also planned for service in space platform (sensor and battle station) defense. This potential role reflected defense planner expectations that future railguns would be capable of rapid fire and on the order of tens to hundreds of shots.<ref>{{cite book | author = David Pahl | title = Space Warfare And Strategic Defense | publisher = Exeter Books | year= 1987 | isbn = 0-86124-378-1 }}</ref>

==Space-based programs==
{{main|Space weapon}}

===Space-Based Interceptor===
The Space-Based Interceptor (SBI) concept involved groups of interceptors housed in orbital modules. Hover testing was completed in 1988 and demonstrated integration of the sensor and propulsion systems. It demonstrated the ability of the seeker to shift its [[aiming point]] from a rocket's hot plume to its cool body, a first for [[infrared]] [[Anti-ballistic missile|ABM]] seekers. Final hover testing occurred in 1992 using miniaturized components similar to those that would have been used in an operational interceptor. These prototypes eventually evolved into [[Brilliant Pebbles]].<ref name="fas">{{cite web|publisher=[[Federation of American Scientists]]|url=https://fas.org/spp/military/program/smc_hist/SMCHOV14.HTM |title=Ballistic Missile Defense |archive-url=https://web.archive.org/web/20150409000653/https://fas.org/spp/military/program/smc_hist/SMCHOV14.HTM |archive-date=April 9, 2015 |access-date=March 10, 2006}}</ref>

===Brilliant Pebbles===
{{main|Brilliant Pebbles}}
[[File:Brilliant pebbles.jpg|thumb|right|Brilliant Pebbles concept artwork]]
Brilliant Pebbles was a non-nuclear system of satellite-based interceptors designed to use high-velocity, watermelon-sized, teardrop-shaped tungsten projectiles as [[Kinetic bombardment|kinetic warheads]].<ref>{{cite web|publisher=[[Claremont Institute]]|url=http://www.missilethreat.com/missiledefensesystems/id.13/system_detail.asp |title=Brilliant Pebbles |archive-url=https://web.archive.org/web/20101019035528/http://www.missilethreat.com/missiledefensesystems/id.13/system_detail.asp |archive-date=October 19, 2010 |access-date=March 11, 2006}}</ref><ref>{{cite web|publisher=[[The Heritage Foundation]] |url=http://www.heritage.org/Research/NationalSecurity/upload/87946_1.pdf |title=Brilliant Pebbles |archive-url=https://web.archive.org/web/20060317104832/http://www.heritage.org/Research/NationalSecurity/upload/87946_1.pdf |archive-date=March 17, 2006 |access-date=March 11, 2006}}</ref> It was designed to operate in conjunction with the [[Brilliant Eyes]] sensor system. The project was conceived in November 1986 by [[Lowell Wood]] at LLNL.<ref>{{cite web|url=http://www.mda.mil/mdalink/html/milstone.html |title=Missile Defense Timeline |archive-url=https://web.archive.org/web/20081224034505/http://www.mda.mil/mdaLink/html/milstone.html |archive-date=December 24, 2008 |publisher=Missile Defense Agency}}</ref> Detailed studies were undertaken by several advisory boards, including the [[Defense Science Board]] and [[JASON (advisory group)|JASON]], in 1989.

The Pebbles were designed so that autonomous operation was possible without external guidance from planned SDI sensor systems. This was attractive as a cost saving measure, as it would allow scaling back of those systems, and was estimated to save $7 to $13&nbsp;billion versus the standard Phase I Architecture.<ref>{{cite web|last=Baucom|first= Donald F. |url=http://highfrontier.org/oldarchive/Archive/hf/The%20Rise%20and%20Fall%20of%20Brilliant%20Pebbles%20-Baucom.pdf|title= The Rise and Fall of Brilliant Pebbles|website=highfrontier.org|access-date=April 24, 2014}}</ref> Brilliant Pebbles later became the centerpiece under the Bush Administration.

[[John Nuckolls|John H. Nuckolls]], LLNL director from 1988 to 1994, described the system as "The crowning achievement of the Strategic Defense Initiative". The sensors and cameras developed for Brilliant Pebbles systems became components of the [[Clementine mission]].<ref>{{cite web|publisher=[[Lawrence Livermore National Laboratory]] |url=http://www.llnl.gov/timeline/1980s/Highlights/pebbles.html |title=Summary of Brilliant Pebbles |archive-url=https://web.archive.org/web/20061012060608/http://www.llnl.gov/timeline/1980s/Highlights/pebbles.html |archive-date=October 12, 2006 |access-date=March 11, 2006}}</ref>

Though regarded as one of the most capable SDI systems, Brilliant Pebbles was canceled in 1994 by BMDO.<ref>{{cite web|publisher=[[Federation of American Scientists]] |url=https://fas.org/spp/starwars/congress/1999_h/s106-339-3.htm |title=Ballistic Missile Defense Technology: Is the United States Ready for A Decision to Deploy? |archive-url=https://web.archive.org/web/20150409020517/https://fas.org/spp/starwars/congress/1999_h/s106-339-3.htm |archive-date=April 9, 2015 |access-date=March 11, 2006}}</ref>

==Sensor programs==
[[File:SDIO Delta Star.jpg|thumb|upright|Delta 183 launch vehicle lifts off, carrying the SDI sensor experiment "Delta Star", March 24, 1989]]
SDIO sensor research encompassed [[visible light]], [[ultraviolet]], [[infrared]], and [[radar]] technologies, and eventually led to the Clementine mission though that mission occurred just after the program transitioned to the [[BMDO]]. Like other parts of SDI, the sensor system initially was very large-scale, but after the Soviet threat diminished it was cut back.

=== Boost Surveillance and Tracking System ===
Boost Surveillance and Tracking System (BSTS) was part of SDIO in the late 1980s, and was designed to detect missile launches, especially during the boost phase; however, once the SDI program shifted toward theater missile defense in the early 1990s, the system left SDIO control and was transferred to the [[United States Air Force|Air Force]].<ref>{{cite web|publisher=[[Federation of American Scientists]] |url=https://fas.org/spp/starwars/program/bsts.htm |title=Boost Surveillance and Tracking System (BSTS)] |archive-url=https://web.archive.org/web/20150408232604/https://fas.org/spp/starwars/program/bsts.htm |archive-date=April 8, 2015 |access-date=March 10, 2006}}</ref>

===Space Surveillance and Tracking System===
{{Redirect|SSTS|"SSTs"|SST (disambiguation){{!}}SST}}
Space Surveillance and Tracking System (SSTS) was a system originally designed for tracking mid-course ballistic missiles. It was designed to work in conjunction with BSTS but was later scaled down in favor of Brilliant Eyes.<ref name="fas"/>

===Brilliant Eyes===
[[Brilliant Eyes]] was a simpler derivative of SSTS that focused on theater ballistic missiles rather than ICBMs and was meant to operate in conjunction with Brilliant Pebbles.

Brilliant Eyes was renamed Space and Missile Tracking System (SMTS) and scaled back further under BMDO, and in the late 1990s it became the low earth orbit component of the Air Force's Space Based Infrared System ([[SBIRS]]).<ref>{{cite web|publisher=[[Federation of American Scientists]]|url=https://fas.org/spp/military/program/warning/smts.htm |title=Space and Missile Tracking System] |archive-url=https://web.archive.org/web/20150409020032/https://fas.org/spp/military/program/warning/smts.htm |archive-date=April 9, 2015 |access-date=March 11, 2006}}</ref>

===Other sensor experiments===
The Delta 183 program used a satellite known as [[Delta Star]] to test sensor-related technologies. Delta Star carried a [[thermographic camera]], a long-wave infrared imager, an ensemble of imagers and [[photometer]]s covering several visible and ultraviolet bands as well as a laser detector and ranging device. The satellite observed several ballistic missile launches including some releasing [[liquid propellant]] as a detection countermeasure.<ref>{{cite web|publisher=The Aerospace Corporation|url=http://www.aero.org/publications/crosslink/summer2001/03.html |title=Delta Star: an SDIO Space Experiment |archive-url=https://web.archive.org/web/20070310123032/http://www.aero.org/publications/crosslink/summer2001/03.html |archive-date=March 10, 2007 |access-date=June 18, 2006}}</ref>

==Countermeasures==
{{verify section|date=June 2024}}
[[File:Ground-Space based hybrid laser weapon concept art.jpg|thumb|An artist's concept of a ground / space-based hybrid laser weapon, 1984]]
In war-fighting, [[countermeasure]]s encompass multiple meanings:

* Immediate tactical action to reduce vulnerability, such as [[Chaff (radar countermeasure)|chaff]], [[decoy]]s, and maneuvering
* Counter strategies that exploit a weakness of an opposing system, such as adding more warheads that are less expensive than the interceptors fired against them.
* Defense suppression - that is, attacking elements of the defensive system.

Countermeasures have long been a key part of warfighting strategy; however, with SDI they attained a special prominence due to the system cost, scenario of a massive sophisticated attack, strategic consequences of a less-than-perfect defense, basing many proposed weapons systems in space, and political debate.

Whereas the [[United States national missile defense]] system targets a relatively limited and unsophisticated attack, SDI planned for a massive attack by a sophisticated opponent. This raised significant issues about economic and technical costs associated with defending against [[anti-ballistic missile defense countermeasures]] used by the attacking side.

For example, if it had been much cheaper to add attacking warheads than to add defenses, an attacker of similar economic power could have simply outproduced the defender. The "cost effective at the margin" requirement was first formulated by [[Paul Nitze]] in November 1985.<ref>{{cite web|first=Marilyn |last=Berger|url=http://www.sais-jhu.edu/pubaffairs/SAISarticles04/Nitze_NYT_102004.pdf |title=Paul Nitze, Cold War Arms Expert, Dies at 97 |archive-url=https://web.archive.org/web/20060910113725/http://www.sais-jhu.edu/pubaffairs/SAISarticles04/Nitze_NYT_102004.pdf |archive-date=September 10, 2006 |publisher=-[[New York Times]]|date=October 20, 2004}}</ref>

In addition, SDI envisioned many space-based systems in fixed orbits, ground-based sensors, command, control and communications facilities, etc. In theory, an advanced opponent could have targeted those, in turn requiring self-defense capability or increased numbers to compensate for attrition.

A sophisticated attacker having the technology to use decoys, shielding, maneuvering warheads, defense suppression, or other countermeasures would have multiplied the difficulty and cost of intercepting the real warheads. SDI design and operational planning had to factor in these countermeasures and the associated cost.

==Response from the Soviet Union==
{{See also|Dead Hand|Biopreparat}}
[[File:President Ronald Reagan meeting with Soviet General Secretary Mikhail Gorbachev at Maison de Saussure during the Geneva Summit.jpg|thumb|SDI was high on [[Mikhail Gorbachev]]'s agenda at the [[Geneva Summit (1985)|Geneva Summit]].]]

SDI failed to dissuade the USSR from investing in development of ballistic missiles.<ref>{{Cite journal|url=http://scienceandglobalsecurity.org/archive/2017/01/did_star_wars_help_end_the_col.html|title=Did Star Wars Help End the Cold War? Soviet Response to the SDI Program|journal=Science & Global Security|year=2017|volume=25|issue=1|pages=3–27|last1=Podvig|first1=Pavel|doi=10.1080/08929882.2017.1273665|bibcode=2017S&GS...25....3P|s2cid=59399449}}</ref> The Soviet response to SDI from March 1983 through November 1985 provided indications of their view of the program both as a threat and as an opportunity to weaken NATO. SDI was likely seen not only as a threat to the physical security of the Soviet Union, but also as part of a larger effort by the United States to seize the strategic initiative in [[arms control]] by neutralizing the military component of Soviet strategy. The Kremlin expressed concerns that space-based missile defenses would make nuclear war inevitable.<ref>{{Cite journal|last1=Lambeth|first1=Benjamin|last2=Lewis|first2=Kevin|date=1988|title=The Kremlin and SDI|url=https://www.jstor.org/stable/20043481|journal=Foreign Affairs|volume=66|issue=4|pages=755–770|doi=10.2307/20043481|jstor=20043481|issn=0015-7120}}</ref>

A major objective of that strategy was the political separation of Western Europe from the United States, which the Soviets sought to facilitate by aggravating allied concern over the SDI's potential implications for European security and economic interests. The Soviet predisposition to see deception behind SDI was reinforced by their assessment of US intentions and capabilities and the utility of military deception in furthering the achievement of political goals.<ref name="Threat and Opportunity: The Soviet View of the Strategic Defense Initiative, Naval Postgraduate School, December 1986">{{cite web|last=Uchrinscko |first=Karl W. |archive-url=https://web.archive.org/web/20120327064308/http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA178649 |archive-date=27 March 2012|url=http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA178649 |title=Threat and Opportunity: The Soviet View of the Strategic Defense Initiative|publisher=Naval Postgraduate School |date=December 1986}}</ref><ref name="The Kremlin and SDI">{{Cite news |last1=Lambeth |first1=Benjamin |last2=Lewis |first2=Kevin |date=1988-03-01 |title=The Kremlin and SDI |url=https://www.foreignaffairs.com/articles/russian-federation/1988-03-01/kremlin-and-sdi |access-date=2024-07-05 |work=Foreign Affairs |language=en-US |volume=66 |issue=4 |issn=0015-7120}}</ref>

[[File:US and USSR nuclear stockpiles.svg|thumb|right|Until the failing [[Soviet economy]] and the [[dissolution of the Soviet Union|dissolution of the country between 1989 and 1991]] which marks the end of the [[Cold War]] and with it the relaxation of the "[[arms race]]", warhead production had continued unabated in the USSR. Total deployed US and Soviet [[strategic weapon]]s increased steadily from 1983 until the Cold War ended.<ref>{{cite web |last=Kristensen |first=Hans M. |year=2012 |title=Michael Krepon - Worth the wait |url=http://krepon.armscontrolwonk.com/archive/3524/worth-the-wait |url-status=dead |archive-url=https://web.archive.org/web/20150112224012/http://krepon.armscontrolwonk.com/archive/3524/worth-the-wait |archive-date=January 12, 2015}}</ref>]]
{{more citations needed section|date=June 2024}}
In 1986 [[Carl Sagan]] summarized what he heard Soviet commentators saying about SDI. They commonly expressed the notion that SDI was equivalent to starting an [[economic warfare|economic war]] through a defensive arms race to further cripple the [[Economy of the Soviet Union#1970–1990|Soviet economy]] with extra [[military spending]]. Another common Soviet perception suggested that SDI served as a disguise for a US desire to initiate a [[Pre-emptive nuclear strike|first strike]] on the Soviet Union.<ref>{{cite web|url=https://www.youtube.com/watch?v=fVUk30GFsL4| archive-url=https://web.archive.org/web/20150711151236/https://www.youtube.com/watch?v=fVUk30GFsL4| archive-date=2015-07-11 | url-status=dead|title=YouTube|via=YouTube}} </ref>

Though classified at the time, a detailed study on a Soviet space-based LASER system began no later than 1976 as the ''Skif'', a 1 MW [[carbon dioxide laser]] along with the anti-satellite ''Kaskad'', an in-orbit missile platform. The devices were reportedly designed to pre-emptively destroy US satellites that might be launched in the future that could otherwise aid US missile defense.

[[File:Ground-based-laser-DIA.jpg|thumb|[[Defense Intelligence Agency|DIA]] drawing of the Soviet Terra-3 laser in the USSR]]
[[Terra-3]] was a Soviet [[laser]] testing centre, located on the [[Sary Shagan]] [[anti-ballistic missile]] (ABM) testing range in the [[Karaganda Region]] of [[Kazakhstan]]. It was originally built to test [[missile defense]] concepts. In 1984, officials within the [[United States Department of Defense]] (DoD) suggested it was the site of a prototypical [[anti-satellite weapon]] system.<ref name=Gadsden1984>{{Cite news  |url=https://news.google.com/newspapers?nid=1891&dat=19840410&id=fqkfAAAAIBAJ&sjid=etYEAAAAIBAJ&pg=2785,2451827 |access-date=2024-07-05 |title=Soviets could have laser able to blind US satellites|newspaper=Gadsden Times|date=April 10, 1984}}</ref>

In 1987 a disguised [[Mir space station]] module was lifted on the inaugural flight of the [[Energia (rocket)|Energia]] booster as the [[Polyus (spacecraft)|Polyus]]. It was later revealed that this craft housed a number of Skif lasers, intended to be clandestinely tested in orbit. However, the spacecraft's [[attitude control system]] malfunctioned upon separation from the booster, and it failed to reach orbit.<ref name="web.archive.org"/> More tentatively, it is also suggested that the Zarya module of the [[International Space Station]], capable of [[Orbital station-keeping|station keeping]] and providing sizable battery power, was initially developed to power the Skif laser system.<ref name="web.archive.org"/>

The Polyus was a prototype of the Skif [[space weapon|orbital weapons platform]] designed to destroy satellites with a megawatt [[Carbon dioxide laser|carbon-dioxide laser]].<ref name=starwars>{{cite web| url = http://www.buran.ru/htm/str163.htm| title = "Звёздные войны, которых не было" (''Star Wars'' that didn't happen)| author = Konstantin Lantratov}}</ref> Soviet motivations behind attempting to launch components of the Skif laser in the form of Polyus were, according to interviews conducted years later, more for propaganda purposes in the prevailing climate of focus on US SDI, than as an effective defense technology, as the phrase "Space based laser" has [[political capital]].<ref name="ReferenceA">{{Cite journal |title=The Star Wars Enigma: Behind the Scenes of the Cold War Race for Missile Defense |first=Nigel |last=Hey|url=http://dx.doi.org/10.1163/2468-1733_shafr_sim250060187 |access-date=2024-07-05 |website=The SHAFR Guide Online|doi=10.1163/2468-1733_shafr_sim250060187 }}</ref>{{clarify|reason=this sentence is awkward and difficult to understand|date=June 2024}}

In 2014, a declassified [[CIA]] paper stated that "In response to SDI, Moscow threatened a variety of military countermeasures in lieu of developing a parallel missile defense system".<ref>{{cite web|url=http://www.businessinsider.com/why-missile-defense-terrified-the-soviets-2014-10?IR=T|title=A Newly Declassified CIA Paper Details A Tense Subplot in the Cold War Arms Race|website=[[Business Insider]]}}</ref><ref>{{cite web|url=https://www.cia.gov/readingroom/docs/DOC_0006122438.pdf|title=Moscow's Response to US Plans for Missile Defense|date=January 19, 2017|archive-url=https://web.archive.org/web/20170119110741/https://www.cia.gov/readingroom/docs/DOC_0006122438.pdf|archive-date=January 19, 2017}}</ref>

==Controversy and criticism==
[[File:SDIO KEW Lexan projectile.jpg|thumb|SDI was not just lasers; in this Kinetic Energy Weapon test, a {{convert|7|g|oz|order=flip|adj=on}} [[Lexan]] projectile was fired from a [[light-gas gun]] at a velocity of {{convert|23000|ft/s|m/s mph}} at a cast aluminum block.]]
Historians from the [[Missile Defense Agency]] attribute the term "Star Wars" to a ''[[Washington Post]]'' article published March 24, 1983. It quoted a speech delivered by Democratic Senator [[Ted Kennedy]] the previous day, describing the proposal as "reckless ''Star Wars'' schemes", a reference to the [[space opera]] film series ''[[Star Wars]]''.<ref>{{cite web|url=http://www.smdc.army.mil/2008/Historical/Eagle/WheredowegetStarWars.pdf|first=Sharon Watkins |last=Lang |title=Where do we get 'Star Wars?'|date=March 2007|publisher=SMDC/ASTRAT Historical Office|work=The Eagle|archive-url=https://web.archive.org/web/20090227050446/http://www.smdc.army.mil/2008/Historical/Eagle/WheredowegetStarWars.pdf|archive-date=27 Feb 2009|url-status=dead}}</ref> Some critics used the term derisively, implying it was an impractical science fiction. In addition, the American media's liberal use of the moniker (despite President Reagan's request) did much to damage the program's credibility.<ref>{{Cite book |last=Kengor |first=Paul |url={{google books|plainurl=yes|id=6yidZucL-KAC|page=181}} |pages=181–183|title=The Crusader: Ronald Reagan and the Fall of Communism |date=2009-10-13 |publisher=Harper Collins |isbn=978-0-06-174099-2 |language=en}}</ref> In comments to the media on March 7, 1986, SDIO Acting Deputy Director Dr. Gerold Yonas described "Star Wars" as an important tool for Soviet [[disinformation]] and asserted that the nickname gave an entirely wrong impression of SDI.<ref>{{cite web |last=Yonas |first=Gerold |date=March 7, 1986 |title=SDI:Prospects and Challenges |url=http://commonwealthclub.org/missiledefense/yonassp.html |url-status=dead |archive-url=https://web.archive.org/web/20100713010908/https://www.commonwealthclub.org/missiledefense/yonassp.html |archive-date=2010-07-13 |website=Missile Defense Forum}}</ref>

[[Jessica Savitch]] reported on the technology in episode No.111 of ''[[Frontline (American TV program)|Frontline]]'', "Space: The Race for High Ground" on November 4, 1983.<ref>{{cite web|url=https://www.imdb.com/title/tt1078741/fullcredits|title="Frontline" Space: The Race for High Ground (TV Episode 1983)|publisher=IMDb}}</ref> The opening sequence shows [[Jessica Savitch]] seated next to a laser that she used to destroy a model of a communication satellite. The demonstration was perhaps the first televised use of a weapons-grade laser. No theatrical effects were used. The model was actually destroyed by the heat from the laser. The model and the laser were realized by Marc Palumbo, a High Tech Romantic artist from the [[MIT Program in Art, Culture and Technology|Center for Advanced Visual Studies]] at MIT.
{{more citations needed section|date=June 2024}}
[[Ashton Carter]], then a board member at [[Massachusetts Institute of Technology|MIT]], assessed SDI for Congress in 1984, noting difficulties in creating an adequate missile defense shield, with or without lasers. Carter said X-rays had a limited scope because they become diffused by the atmosphere, much like the beam of a flashlight spreading outward in all directions. This means the X-ray sources needed to be close to the Soviet Union, especially during the boost phase, for the Soviet missiles to be both detectable to radar and targeted by the lasers. Opponents disagreed, saying advances in technology, such as using stronger beams, and by "bleaching" the column of air surrounding the laser beam, could increase the distance that the X-ray could travel to successfully hit its target.{{citation needed|date=June 2024}}

Physicists [[Hans Bethe]] and [[Richard Garwin]], who worked with Teller on both the atomic bomb and hydrogen bomb at [[Los Alamos National Laboratory|Los Alamos]], claimed a laser defense shield was unfeasible. They said that a defensive system was costly and difficult to build yet simple to destroy and claimed that the Soviets could easily use thousands of decoys to overwhelm it during a [[nuclear attack]]. They dismissed the idea of a technical solution to the [[Cold War]], saying that a defense shield could be viewed as threatening because it would inhibit Soviet offensive capabilities while leaving America's offense intact. In March 1984, Bethe coauthored a 106-page report for the [[Union of Concerned Scientists]] that concluded "the X-ray laser offers no prospect of being a useful component in a system for ballistic missile defense."<ref name="UCS">{{Cite journal |last1=Bethe |first1=Hans A. |last2=Garwin |first2=Richard L. |last3=Gottfried |first3=Kurt |last4=Kendall |first4=Henry W. |date=1984 |title=Space-based Ballistic-Missile Defense |url=https://www.jstor.org/stable/24969454 |journal=Scientific American |volume=251 |issue=4 |pages=39–49 |doi=10.1038/scientificamerican1084-39 |jstor=24969454 |bibcode=1984SciAm.251d..39B |issn=0036-8733}}</ref>

In response, when Teller testified before Congress he stated that "instead of [Bethe] objecting on scientific and technical grounds, which he thoroughly understands, he now objects on the grounds of politics, on grounds of military feasibility of military deployment, on other grounds of difficult issues which are quite outside the range of his professional cognizance or mine."<ref>{{cite book|last=Lett|first=Donald G.|title=Phoenix Rising: The Rise and Fall of the American Republic|year=2008|publisher=AuthorHouse|location=United States|page=264}}</ref>

On June 28, 1985, [[David Parnas|David Lorge Parnas]] resigned from SDIO's Panel on Computing in Support of Battle Management, arguing in eight short papers that the SDI software could never be made trustworthy and that such a system would inevitably be unreliable and menace humanity in its own right.<ref name="Parnas85">{{cite web|last=Parnas |first=D.L.|url=http://klabs.org/richcontent/software_content/papers/parnas_acm_85.pdf |title=Software Aspects of Strategic Defense Systems |archive-url=https://web.archive.org/web/20110927074918/http://klabs.org/richcontent/software_content/papers/parnas_acm_85.pdf |archive-date=September 27, 2011 |publisher=Communications of the ACM|date=December 1985|volume=28 |issue=12}}</ref> Parnas said he joined the panel with the desire to make nuclear weapons "impotent and obsolete" but soon concluded that the concept was "a fraud".

[[File:Keinen Krieg der Sterne.JPG|thumb|SDI drew criticism from abroad as well. This 1986 [[Socialist German Workers Youth]] graffiti in [[Kassel|Kassel, West Germany]] says "Keinen Krieg der Sterne! Stoppt SDI! SDAJ" or (No star wars! Stop SDI! [[Socialist German Workers Youth|SDAJ]]).]]

===Treaty obligations===
Another criticism of SDI argued that it would require the United States to modify existing treaties. The [[Outer Space Treaty]] of 1967 required "States Party to the Treaty undertake not to place in orbit around the Earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner."<ref>{{cite book |title=Nuclear weapons and contemporary international law |last1=Singh |first1=Nagendra |last2=McWhinney |first2=Edward |year=1989 |publisher=Martinus Nijhoff |isbn=90-247-3637-4 |page=236 |url=https://books.google.com/books?id=r2IfMEpPUIsC&pg=PA236}}</ref> This clause forbade the US from pre-positioning in Earth orbit any devices powered by nuclear weapons and any devices capable of "mass destruction". A space-stationed nuclear-pumped X-ray laser would have violated this treaty, since other SDI systems did not require the pre-positioning of nuclear explosives in space.
{{more citations needed section|date=June 2024}}
The [[Anti-Ballistic Missile Treaty]] and its subsequent protocol,<ref>{{cite web|url=https://fas.org/nuke/control/abmt/text/abmprot1.htm |title=Protocol to the Treaty between the United States of America and the Union of Soviet Socialist Republics on the Limitation of Anti-Ballistic Missile Systems|date=May 24, 1976}}</ref> which limited missile defenses to one location per country at 100 missiles each ([[ABM-1 Galosh|which the USSR had]] and the US did not), would have been violated by SDI ground-based interceptors. The [[Nuclear Non-Proliferation Treaty]] requires "Each of the Parties to the Treaty undertakes to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control." Many{{Who|date=October 2009}} viewed deployment of ABM systems as an escalation, and therefore a violation of this clause, although this view was not universal.{{citation needed|date=June 2024}}

=== Mutual assured destruction ===
SDI threatened to disrupt the strategic equilibrium ensured by the doctrine of [[mutual assured destruction]]. MAD postulated that neither the U.S. nor the USSR could attack the other without considering the strong probability that both sides would be annihilated.<ref>{{cite web |title=Strategic Defense Initiative (SDI) - Nuclear Museum |url=https://ahf.nuclearmuseum.org/ahf/history/strategic-defense-initiative-sdi/ |website=Atomic Heritage Foundation |access-date=5 June 2024 |archive-url=https://web.archive.org/web/20240522075523/https://ahf.nuclearmuseum.org/ahf/history/strategic-defense-initiative-sdi/ |archive-date=22 May 2024 |url-status=live}}</ref> A defensive weapon system that could neutralize much of an adversary's nuclear counter-strike force would potentially embolden the possessor to strike first.<ref>{{cite web |title=The Strategic Defense Initiative — The Other "Star Wars" |url=https://adst.org/2015/11/the-strategic-defense-initiative-the-other-star-wars/ |website=Association for Diplomatic Studies and Training |access-date=5 June 2024 |archive-url=https://web.archive.org/web/20240201184919/https://adst.org/2015/11/the-strategic-defense-initiative-the-other-star-wars/ |archive-date=1 Feb 2024 |url-status=live}}</ref>

During the [[Reykjavík Summit|Reykjavik talks]] with [[Mikhail Gorbachev]] in 1986, Reagan addressed Gorbachev's concerns about imbalance by stating that SDI technology could be provided to the entire world – including the Soviet Union – to prevent the imbalance from occurring. Gorbachev answered dismissively. When Reagan proposed technology sharing again, Gorbachev stated "we cannot assume an obligation relative to such a transition", referring to the cost of implementing such a program.<ref name="CNNep22">{{cite news |url=http://www.cnn.com/SPECIALS/cold.war/episodes/22/documents/reykjavik/ |title=Reagan-Gorbachev Transcripts |website=[[CNN]] |access-date=May 14, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20080119172055/http://www.cnn.com/SPECIALS/cold.war/episodes/22/documents/reykjavik/ |archive-date=January 19, 2008}}</ref>

===Whistleblower===
In 1992, scientist [[Aldric Saucier]] was given [[whistleblower protection in the United States|whistleblower protection]] after he was fired and complained about "wasteful spending on research and development" at SDI.<ref name="nytimesscientistsaidtoassertfraud">{{cite news|title=Scientist Said to Assert Fraud in 'Star Wars'|url=https://www.nytimes.com/1992/03/02/us/scientist-said-to-assert-fraud-in-star-wars.html|access-date=August 26, 2017|work=The New York Times|date=March 2, 1996}}</ref> Saucier lost his [[security clearance]].<ref name="washpostlardner">{{cite news|last1=Lardner| first1=George Jr. |title=Army Accuses SDI Critic of Falsifying Credentials|url=https://www.washingtonpost.com/archive/politics/1992/04/14/army-accuses-sdi-critic-of-falsifying-credentials/13ffe75f-50f8-4654-9027-536c30880c13/|access-date=August 26, 2017|newspaper=The Washington Post|date=April 14, 1992}}</ref>

==Timeline==
<timeline>
ImageSize  = width:700 height:700
PlotArea   = left:40 right:30 top:10 bottom:20
DateFormat = mm/dd/yyyy
TimeAxis   = orientation:vertical order:normal format:yyyy
Period     = from:1983 till:1993
AlignBars  = early
ScaleMajor = unit:year increment:1 start:1983
ScaleMinor = unit:month increment:6 start:01/01/1983
Colors =
  id:gray value:gray(0.7)

# there is no automatic collision detection,
# so shift texts up or down manually to avoid overlap

Define $dx = 25 # shift text to right side of bar

PlotData =
  bar:event width:20 color:blue shift:($dx,-4)

  from:start till:end color:blue

  mark:(line, white)

  at:03/08/1983 text:"March 23, 1983, Reagan "Star Wars" speech."
  at:03/27/1984 text:"March 27, 1984, Lt. Gen. James A. Abrahamson was appointed as first Director of the SDIO."
  at:06/10/1984 text:"June 10, 1984, the Army demonstrated Hit-to-kill capability in the Homing Overlay Experiment (HOE)."
  at:09/06/1985 text:"September 6, 1985, the Mid-Infrared Advanced Chemical Laser destroyed a ground-based Titan booster during a test."
  at:07/30/1986 text:"July 30, 1986, General Abrahamson directed that SDIO be reorganized."
  at:11/01/1986 text:"November 1986, The formation of the concept for Brilliant Pebbles."
  at:07/01/1987 text:"June–July, 1987, Strategic Defense System Phase I baseline architecture was approved."
  at:09/30/1988 text:"September 30, 1988, The SDI Organization was realigned adding several new positions."
  at:02/01/1989 text:"February 1, 1989, Lt. Gen. George L. Monahan, Jr., became the second director of the SDIO."
  at:08/01/1989 text:"August 1989, Four major studies of the Brilliant Pebbles concept concluded that it was promising and technically feasible."
  at:11/09/1989 text:"November 9, 1989, fall of the Berlin wall and end of the Cold War."
  at:07/10/1990 text:"July 10, 1990, Ambassador Henry F. Cooper became the third director of the SDIO."
  at:01/29/1991 text:"January 29, 1991, George H.W. Bush's State of the Union address refocusing SDI towards GPALS."
  at:12/31/1991 text:"December 26, 1991, the end of the Soviet Union."

  at:05/13/1993 text:"May 13, 1993, SDIO renamed BMDO by Clinton administration."
</timeline>

==See also==<!-- New links in alphabetical order please -->
{{div col}}
* [[Anti-ballistic missile]]
* [[Anti-satellite weapon]]s
* [[Ballistic Missile Defense Organization]] (BMDO)
* [[Comparison of anti-ballistic missile systems]]
* [[Directed-energy weapon]]s
** [[Zenith Star]]
* [[Ground-Based Midcourse Defense]] (GMD)
* [[International Conference of Laser Applications]]
* [[Militarisation of space|Militarization of space]]
* [[Missile Defense Agency]] (MDA)
* [[Missile defense systems by country]]
* [[Polyus (spacecraft)]]
* [[Rockwell X-30]]&nbsp;– partly funded by the SDIO
* [[THAAD]] missile defense system
* [[United States national missile defense]]
* [[United States Space Force]]
{{div col end}}

==References==
{{reflist}}

===Works cited===
{{refbegin}}
* {{cite book|title=Way Out There in the Blue: Reagan, Star Wars and the End of the Cold War|author=Frances Fitzgerald|publisher=Simon & Schuster|year=2001|isbn=0-7432-0023-3|author-link=Journalist}}
* {{cite book | first=William J. | last=Broad | year=1985 | title=Star Warriors: A penetrating look into the lives of the young scientists behind our space age weaponry. | publisher=Simon & Schuster | isbn=0-7881-5115-0}} (Reprint edition 1993; Diane Pub. Co.)
* {{cite book |last=Kent |first=Glenn |title=Thinking About America's Defense |publisher=RAND |url=https://archive.org/details/thinkingaboutame0000kent |year=2008 |isbn=978-0-8330-4452-5 |url-access=registration }}
* {{cite tech report |last=Jayne |first=Edward Randolph |url=http://dspace.mit.edu/bitstream/handle/1721.1/14577/19300718.pdf |publisher=Massachusetts Institute of Technology |title=The ABM debate: strategic defense and national security |access-date=13 December 2014 |date=1969 |oclc=19300718 }}
* {{cite book |last= Ritter |first= Scott |title= Dangerous Ground: America's Failed Arms Control Policy, from FDR to Obama |publisher= Nation Books |url= https://archive.org/details/dangerousgrounda00scot |url-access= registration |year=2010 |isbn= 978-0-7867-2743-8 }}
{{refend}}

==Further reading==
* Bateman, Aaron (2024). ''[https://direct.mit.edu/books/oa-monograph/5770/Weapons-in-SpaceTechnology-Politics-and-the-Rise Weapons in Space: Technology, Politics, and the Rise and Fall of the Strategic Defense Initiative]''. The MIT Press. 
* {{cite book | first=William J. | last=Broad | year=1992 | title=Teller's War: The Top-Secret Story Behind the Star Wars Deception. | place=New York | publisher=Simon & Schuster}}
* {{Cite book |first1=Gary |last1=Guertner |first2=Donald |last2=Snow |title=The Last Frontier: An Analysis of the Strategic Defense Initiative |date=1986 |publisher=D.C. Heath and Company |isbn=0-669-12370-6}}
* {{cite book | first=Edward Tabor | last=Linenthal | year=1989 | title=Symbolic Defense: The Cultural Significance of the Strategic Defense Initiative. | place=Urbana, Ill. | publisher=University of Illinois Press}}
* {{Cite book|first1=Keith |last1=Payne | title=Strategic Defense: "Star Wars" in Perspective |date=1986 |publisher=Hamilton Press |isbn=0-8191-5109-2 |url=https://archive.org/details/strategicdefense00payn |url-access=registration }}
*{{cite web|last=Saltoun-Ebin|first=Jason|title=The Strategic Defense Initiative |url=https://www.thereaganfiles.com/document-collections/sdi.html |website=The Reagan Files |access-date=5 June 2024 |archive-url=https://web.archive.org/web/20240114152625/https://www.thereaganfiles.com/document-collections/sdi.html |archive-date=14 Jan 2024 |url-status=live}}
* ''Weapons in Space'', 2 vols. ''[[Daedalus (journal)|Daedalus]]'' 114, nos. 2 (Spring 1985) & 3 (Summer 1985).

==External links==
{{Commons category}}
*[https://www.reaganlibrary.gov/archives/topic-guide/strategic-defense-initiative-sdi Strategic Defense Initiative – Ronald Reagan Presidential Library]

{{Presidency of Ronald Reagan}}
{{Cold War}}
{{Politics of outer space}}
{{Authority control}}

[[Category:Strategic Defense Initiative| ]]
[[Category:1983 in military history]]
[[Category:Abandoned military projects of the United States]]
[[Category:Foreign relations of the United States]]
[[Category:Military history of the United States]]
[[Category:Missile defense]]
[[Category:Presidency of Ronald Reagan]]
[[Category:Reagan administration controversies]]
[[Category:Soviet Union–United States relations]]
[[Category:Space weapons]]
[[Category:1984 establishments in the United States]]
[[Category:Organizations established in 1984]]
[[Category:Directed-energy weapons of the United States]]
[[Category:Military space program of the United States]]
[[Category:Cold War terminology]]
[[Category:1983 in American politics]]