with this problem, Dwight D. Eisenhower asked ARPA to consider alternative concepts. Their Project Defender studied all sorts of systems, before abandoning most of them to concentrate on Project BAMBI. BAMBI used a series of satellites carrying interceptor missiles that would attack the Soviet ICBMs shortly after 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 would be enormous, and the US Air Force continually rejected such concepts. Development was cancelled in 1963. Through 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. After thirty years of effort, only one such system would be built; a single base of the original Safeguard system became operational in April 1975, only to shut down 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 George Shultz, Reagan's secretary of state, suggested that a 1967 lecture by physicist Edward Teller (the so-called "father of the hydrogen bomb") 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 being a contemporary enhanced thermal/X-ray device used actively on the Spartan missile in 1975. Held at Lawrence Livermore National Laboratory (LLNL), the 1967 lecture was attended by Reagan shortly after he became the 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 as the Skif, a 1 MW Carbon dioxide laser along with the anti-satellite Kaskad, an 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