Strategic Defense Initiative
The Strategic Defense Initiative, derisively nicknamed the Star Wars program, was a proposed missile defense system intended to protect the United States from attack by ballistic nuclear missiles. The program was announced in 1983 by President Ronald Reagan, a vocal critic of the doctrine of mutual assured destruction, which he described as a "suicide pact". Reagan called for a system that would end MAD and render nuclear weapons obsolete. Elements of the program reemerged in 2019 under the Space Development Agency.
The Strategic Defense Initiative Organization was set up in 1984 within the US Department of Defense to oversee development. Advanced weapon concepts, including lasers, particle-beam weapons, 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. Under SDIO's Innovative Sciences and Technology Office, 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.
SDI was heavily criticized for threatening to destabilize MAD and re-ignite "an offensive arms race". Senator Ted Kennedy derided the program as "reckless Star Wars schemes", a reference to the space opera film series Star Wars, leading to the popularisation of the monicker. In a 1986 speech, Senator Joe Biden argued that, "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." 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. 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.
Declassified intelligence material revealed that through 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. 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 missiles and renamed the agency the Ballistic Missile Defense Organization.
In 2019, elements, specifically the observation portions, of the program re-emerged with President Trump's signing of the National Defense Authorization Act. The program is managed by the Space Development Agency as part of the new National Defense Space Architecture. CIA director Mike Pompeo called for additional funding to achieve a full-fledged "Strategic Defense Initiative for our time, the SDI II." On May 20 2025, Donald Trump announced the Golden Dome, a project broadly similar to SDI, which he referenced in the announcement.
History
National BMD
The US Army considered the issue of ballistic missile defense 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 noted that longer-range missiles, though faster, had longer flight times that eased the timing issue. Their high altitudes also made them easier to detect with long-range radar.This led to successive programs—Nike Zeus, Nike-X, Sentinel, and ultimately Safeguard—each seeking to defend against 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 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 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.
File:LIM-49A Spartan mockup.png|thumb|The Extended Range Nike Zeus/Spartan missile of the late-1960s was designed to provide full-country defense as part of the Sentinel-Safeguard programs. Projected to cost $40 billion, the system was expected to provide only limited protection in the event of a large-scale Soviet strike.
President Dwight D. Eisenhower asked 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. The projected operational costs were prohibitive, and the U.S. Air Force ultimately rejected the concept. Development was cancelled in 1963.
By the late 1960s, ballistic missile defense had become highly controversial. Public meetings on the Sentinel system drew thousands of protesters, reflecting growing opposition to its deployment. 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.
A Soviet military A-35 anti-ballistic missile system was deployed around Moscow to intercept enemy ballistic missiles 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 until the 1990s, it featured the nuclear-tipped A350 exoatmospheric interceptor missile.
Lead up to SDI
, Reagan's 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 weapons, principally the W65 and W71, with the latter an enhanced thermal/X-ray device used on the Spartan missile in 1975. Held at Lawrence Livermore National Laboratory, the 1967 lecture was attended by Reagan shortly after he became governor of California.Development of laser weapons in the Soviet Union began in 1964–1965. Though classified at the time, a detailed study on a Soviet space-based laser system began no later than 1976 with the 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.
A revolver cannon was mounted on the 1974 Soviet Salyut 3 space station, a satellite that successfully test-fired its cannon in orbit.
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, 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 synthesize a missile gap.
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. 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.
In the fall of 1979, at Reagan's request, Lieutenant General Daniel O. Graham, the former head of the 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 MAD doctrine.
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 that examined in greater detail how the system would function.
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. New developments under Project Excalibur by Teller's "O-Group" at LLNL suggested that a single X-ray laser could shoot down dozens of missiles with a single shot. The groups began to meet in order to prepare their plans for the incoming US president Reagan.
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 Reagan 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.