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 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. /
Spartan missile of the late-1960s was designed to provide full-country defense as part of the Sentinel-
Safeguard programs. Projected to cost $40 billion ($ billion in ), the system was expected to provide only limited protection in the event of a large-scale Soviet strike. President
Dwight D. Eisenhower asked
DARPA 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. until the 1990s, it featured the nuclear-tipped
A350 exoatmospheric interceptor missile.
Lead up to SDI 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, 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 (LLNL), 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 (
Rikhter R-23) 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 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. 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 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. ==Project and proposals==