How and why did relations change between the Superpowers between 1963 and 1979?

set up directly linking the White House and the Kremlin, it enabled the two leaders to communicate properly but was barely used. However the hot line was more symbolic rather than helpful and this was definitely a step forwards. A test ban treaty was signed which allowed nuclear weapon testing only allowed beneath the ground. This was also not very helpful as most of the testing was done underground anyway but it was also symbolised co-operation. The relationship had not been this good since 1945. In 1964 Khrushchev was replaced by Brezhnev, Brezhnev encouraged the Soviet military might and was particularly interested in continuing the arms race. Détente seemed impossible. In 1965 Us troops were sent into Vietnam under the orders of President Truman, Brezhnev saw this as a threatening act and decided to get revenge. He sent Warsaw Pact troops into Czechoslovakia in 1968 in an attempt to influence and intimidate the Czech Prime Minister, Dubeck. As Czechoslovakia was a Soviet ruled country and Dubeck was allowing personal freedoms that went against communism, Brezhnev sent 20,000 troop in and sacked Dubeck. Johnson felt exactly the same Brezhnev had felt about Vietnam. Between 1968 and 1977 détente seemed surprisingly possible again. In 1968 a Nuclear Non-Proliferations Treaty was signed, it meant that the Superpowers were agreeing to not supply nuclear technology to other countries. In 1972 SALT I (Strategic Arms Limitation Talks) was signed, this limited the numbers of nuclear missiles. Also in 1972 both sides agreed to begin MBFR (Mutual and Balanced Force Reduction Talks) which continued to the 1980s. 1974 marked the beginning of SALT II. Both sides agreed on further reductions in strategic weapons, however SALT II never actually came into affect. In 1975 the Helsinki agreement was signed on Human rights. This meant that the USA, the USSR and 33 other countries were guaranteed respect, freedom of thought, religion, belief and no discrimination between races, sex’s, language or religion. This was massively symbolic in an attempt on both sides o move towards détente and until 1977 it seemed like it was going to happen.However, in 1977 there was a complete collapse of détente. At the Belgrade conference, President Carter criticised the USSR human rights. A pro-Soviet government was running in Iran and Guerrillas seized power in Nicaragua with communist support. which worried the USA. Both Superpowers were increasing their weapons, the USSR weapons were set up in the Eastern bloc and NATO retaliated by placing Cruise and Pershing missiles in Europe. Communism leaked into Afghanistan and the USA stopped grain exports to the USSR. All this lead to a collapse in détente after years of aiming for it. In just 16 years the relationship between the Superpowers went from optimistic to a collapse to more attempts t co-operation just to collapse again. By 1979 the two countries had got no where in reaching détente, the Cold War clearly left its affects behind for many years to come. The main reason for the frequent lapse in détente, I think was the appointment of Brezhnev and the USA stopping exports of grain reaching the USSR.