ballistic missiles (SLBMs). As part of the SALT process, the ABM Treaty was also signed. The SALT agreements were generally considered in the West as having codified the concept of Mutually assured destruction (MAD), or deterrence. Both the U.S. and the Soviet Union recognized their mutual vulnerability to massive destruction, no matter which state launched nuclear weapons first. A second SALT agreement, SALT II, was signed in June 1979 in Vienna. Among other provisions, it placed an aggregate ceiling on ICBM and SLBM launchers. The second SALT agreement was never ratified by the United States Senate, in large part because of the breakdown of détente in the late 1970s and early 1980s. At one time, the Soviet Union maintained the world's largest nuclear arsenal in history. According to estimates by the Natural Resources Defense Council, the peak of approximately 45,000 warheads was reached in 1986. Roughly 20,000 of these were believed to be tactical nuclear weapons, reflecting the Red Army doctrine that favored the use of these weapons if war came in Europe. The remainder (approximately 25,000) were strategic ICBMs. These weapons were considered both offensive and defensive in nature. The production of these weapons is one of the factors that led to the collapse of the Soviet Union. Military-industrial complex and the economy With the notable exception of Khrushchev and possibly Gorbachev, Soviet leaders from the late 1920s onwards emphasized military production over investment in the civilian economy. The high priority given to military production traditionally enabled military-industrial enterprises to commandeer the best managers, labor, and materials from civilian plants. As a result, the Soviet Union produced some of the world's most advanced armaments. In the late 1980s, however, Gorbachev transferred some leading defense-industry officials to the civilian sector of the economy in an effort to make it as efficient as its military counterpart. The integration of the party, government, and military in the Soviet Union became most evident in the area of defense-related industrial production. Gosplan, the state planning committee, had an important role in directing necessary supplies and resources to military industries. The Soviet Defense Council made decisions on the development and production of major weapons-systems. The Defense Industry Department of the Central Committee supervised all military industries as the executive agent of the Defense Council. Within the government, a Deputy Chairman of the Council of Ministers headed the Military Industrial Commission, which coordinated the activities of