The following summer the Soviet Union, the United States and Great Britain sign the Limited Test Ban Treaty. By 1964, Robert McNamara concludes that as the Soviet Union continues to build up its nuclear forces, the Americans can no longer destroy all the Soviet forces. Civil defense is taken seriously in the Soviet Union, though less so in the United States. Five A U.S. plane carrying four hydrogen bombs collides with a tanker aircraft over the coast of Spain in 1967. Three bombs fall on land and one is lost at sea.
Radioactive plutonium contaminates the village of Palomares.
The Americans have been developing an ABM system but McNamara convinces President Johnson to abandon ABMs if the Soviets agree to do the same. To reduce tensions caused by the 1967 Six-Day War in the Middle East, President Johnson and Soviet Premier Kosygin agree to meet in Glassboro, New Jersey. McNamara wants the Soviets to abandon ABMs. As a result of the Strategic Arms Limitation Talks, the superpowers agree to limit ABMs and temporarily freeze missile launchers. In the 1970s, America and Russia add 12,000 nuclear warheads to their missile forces.