Strategic Defense Initiative

Origins

The concept drew on the national missile defense programs of the 1960s (Nike Zeus, Nike-X, Sentinel, Safeguard) and on space-based interception studies such as BAMBI and Project Defender. Reagan heard Edward Teller explain directed-energy weapons at Lawrence Livermore in 1967, and in 1979 he visited NORAD at Cheyenne Mountain, where he was told an incoming missile could be tracked but not stopped. Daniel Graham's 'High Frontier' proposal was a further antecedent.

Announcement and organization

In his nationally televised speech of 23 March 1983 Reagan called upon the scientific community to give the United States the means of rendering nuclear weapons 'impotent and obsolete.' The same day Senator Ted Kennedy attacked 'reckless Star Wars schemes,' and the nickname spread. SDIO was established in January 1984, and on 27 March 1984 Lt. Gen. James Abrahamson was appointed its first director. By 1985 SDIO served as an umbrella for 22 think tanks and aerospace firms.

Technical bets

Early work pursued the X-ray laser (the nuclear-pumped Excalibur), the chemical laser MIRACL, space-based lasers, neutral particle beams, the railgun CHECMATE, and kinetic interceptors (HOE, ERIS, HEDI); space-based interceptors evolved into Brilliant Pebbles, proposed in 1986 by Lowell Wood and Edward Teller. On 10 June 1984 the HOE4 test achieved the first successful exoatmospheric hit-to-kill intercept, but a 1993 press report showed the target had been rigged, and a GAO investigation confirmed Congress had never been told of enhancements to the target vehicle.

Criticism and reorientation

Bethe and Garwin argued that a laser shield was unfeasible and easily overwhelmed by decoys, and a March 1984 Union of Concerned Scientists report concluded the X-ray laser offered no useful prospect. In June 1985 David Parnas resigned from SDIO's battle-management computing panel, calling the concept 'a fraud.' An American Physical Society review (presented 1986, released in redacted form in early 1987) found no candidate directed-energy system near deployment, and budgets were cut. SDIO shifted in late 1986 to the High Frontier-derived 'Strategic Defense System, Phase I Architecture,' and in 1990 took Brilliant Pebbles as its baseline. GPALS, approved by George H. W. Bush in 1991, aimed to intercept up to 200 missiles and cut a decade's cost from $53bn to $41bn.

Arms control

SDI was one of the most significant obstacles to space arms control. At the Reykjavík summit of 11–12 October 1986 the two sides came close to eliminating all nuclear weapons, but the talks collapsed when Gorbachev made it conditional on confining SDI research to laboratories for ten years and Reagan refused any limits on SDI. Reagan counter-proposed eliminating all ballistic missiles within ten years along with the right to deploy strategic defenses afterwards, and offered to share SDI technology; Gorbachev dismissed the sharing offer. In February 1987 Gorbachev delinked SDI from the intermediate-range talks, enabling the December 1987 INF Treaty; no START agreement was reached before Reagan left office.

Soviet response

Yuri Andropov accused the United States of seeking a first-strike capability after the announcement. Soviet planners developed an 'asymmetric response': raising the survivability of strategic nuclear forces, improving penetration of any ABM layer, and building means to destroy space battle stations and relay mirrors. The Skif 1 MW CO2 laser and the Kaskad anti-satellite platform were pursued, and Polyus, launched aboard Energia on 15 May 1987, failed to reach orbit.

It has been claimed that SDI drove the USSR into an arms race that hastened its collapse, but this should not be presented as established fact. Some critics, among them Omand citing Gordievsky's advice to Reagan, have argued that the real aim was to undermine the Soviet economy; that account rests on memoir and opinion. Declassified documents indicate instead that Gorbachev's advisers judged asymmetric countermeasures viable and cost-effective, and that pressure from SDI was 'not a significant factor' in his February 1987 decision. Soviet ABM research predated SDI, and in 1983 Gorbachev said the program 'will sweep the world into a new stage of the arms race and would destabilize the strategic situation.'

Relations and legacy

Reagan and Gorbachev confronted each other over SDI at the Geneva, Reykjavík, Washington and Moscow summits. Soviet leaders and allied governments including Britain's feared that an effective defense would make a first strike possible and trigger a new arms race; Sakharov held SDI to be more dangerous than MAD. The 1972 ABM Treaty limited each party to two ABM complexes (one after 1974), and SDI's ground-based interceptors and space-based testing were widely seen as inconsistent with it. The United States withdrew from the treaty only in 2002 (Bush, notice in December 2001, effective June 2002). SDI was never formally cancelled: in 1993 the Clinton administration renamed SDIO the Ballistic Missile Defense Organization and redirected it to theater ballistic missiles and ground-based interceptors, abandoning space-based interceptors. The agency became the Missile Defense Agency in 2002. Elements re-emerged in 2019 under the Space Development Agency, and the 2025 'Golden Dome' system is described as broadly similar to SDI and an extension of it.