The two global superpowers, the USA and USSR, were locked into a nuclear arms race with both sides building and developing large arsenals of nuclear weapons, including the hydrogen bomb and antiballistic missiles. Both the USSR and the USA had developed intercontinental ballistic missiles with a minimum range of 3,400 miles (5,470 km), with each missile capable of delivering more than one thermal nuclear warhead. In 1970, each side had between 25,000–30,000 warheads. Air, land and naval missile bases were scattered throughout their territories and additionally in Warsaw Pact and NATO countries. In the Strategic Arms Limitation Talks 1 (SALT 1) from 1969–72 between President Richard Nixon (USA) and General Secretary Leonid Brezhnev (Soviet Union), both superpowers agreed to limit their Intercontinental Ballistic Missiles. However, the agreement, spanning five years, did not cover the newer and more destructive MIRVs (Multiple Independently Targetable Re-entry Vehicle), which carried nuclear bomb clusters in one warhead. By 1970 the two superpowers had sufficient nuclear weaponry to ensure mutually assured destruction (MAD). They had created a nuclear standoff, meaning that the consequences of either side initiating a nuclear attack would be so catastrophic that they were locked into a terrifying stalemate.
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