The
Strategic Arms Limitation talks that began in November 1969 resulted in two
agreements, which were signed by U.S. President Richard Nixon and Soviet President
Leonid Brezhnev in May 1972. The more enduring was the Anti-Ballistic Missile (ABM) Treaty, which initially limited both sides to two ABM sites, one to protect each capital city, and one to protect a designated “missile field” with a heavy concentration of Intercontinental Ballistic Missiles (ICBMs). Later the two sides agreed to reduce authorization from two ABM sites to one each. The United States chose to protect its missile site at Grand Forks, North Dakota, while the Soviet Union chose Moscow. Both sides recognized that ABM systems were chiefly ineffective – the technology was not that advanced – and highly expensive. As a result, neither country built effective or comprehensive ABM sites. For many years, the Soviet Union continued to invest in the system around Moscow, known by its NATO codename, Galosh, but the United States moved its Grand Forks project into inactive status in 1976.
The ABM Treaty, which President George W. Bush decided to abrogate in December 2001, was long regarded as a cornerstone of strategic stability. This is because the treaty established as a fundamental premise that if defensive systems were limited, then neither side would be tempted to launch a first strike with nuclear weapons. Without a defensive shield to hide behind, either side would face an overwhelming retaliatory attack if it decided to strike first. The concept, often called “mutual assured destruction,” could also be regarded as “mutual assured deterrence,” because leaders on both sides recognized the futility and terrible consequences in initiating nuclear war, and hence were deterred from contemplating such an attack.
The second agreement – called the Interim Agreement on limiting strategic arms, or SALT 1 – was signed by the two leaders at the same ceremony. It was designed to curtail the spiraling nuclear arms race by limiting the number of U.S. and Soviet ICMB silos and submarines capable of carrying submarine-launched ballistic missiles (SLBMs). Under SALT I, the United States was limited to 1,054 ICMB silos and 656 SLBM launch tubes. The Soviet Union’s ICBM silos were capped at 1,607 and its SLBM launch tubes were capped at 740.
The agreement ignored the size of strategic bomber forces, and while agreeing not to “significantly” increase the size of individual silos, did leave open the possibility of putting multiple warheads on each ICMB and SLBM. This proved to be a flaw in the SALT I agreement because the United States and the Soviet Union quickly began a competition to deploy multiple warheads on missiles. At the time the treaty was signed, the United States had a significant technological lead in the creation of Multiple Independently Targeted Re-entry Vehicles (MIRVs) – a term referring to the then-new U.S. ability to put as many as 10 separate nuclear warheads in the nose cone of one missile, each programmed to hit a separate target after it was released during the missile’s re-entry into the atmosphere. However, the Soviet Union quickly caught up with the United States in this area, and over the next two decades the two countries each deployed about 10,000 nuclear warheads on strategic missiles.
Subsequent strategic arms reduction agreements rectified this problem, further reducing the size of the two strategic arsenals, increasing the reliability of verification measures, and, as with the ABM Treaty, channeling and limiting development of certain types of strategic technologies to prevent one side from “breaking out” of a state of rough parity that would spark another spiraling arms race.