Both USA and USSR had the atomic bomb. They began to pour money into projects to build more and bigger bombs and new delivery systems.

MAD- Mutually assured destruction
Both sides suspected the other side would build up enough weapons to 'strike first' and in doing so wipe out the other side so they couldn't strike back.

Increasing tension forcing this process of creating weapons to not slow down

A competition between USA and USSR to build up the biggest and most powerful supply of weapons+ military might (nuclear and non-nuclear)

6 years after NATO Soviet Union set up the Warsaw pact. Military alliance of eight nations headed by the Soviet Union. They were to support each other if attacked

Created the existence of the two rival alliance systems in the Cold War- NATO in the west and Warsaw pact in the East > Increased rivalry between USA and USSR and intensified arms race

Stalin died 1953
No change in Soviet control when deputy Georgy Malenkov took over control
After 2 years Khruschev took control and within a year he had denounced Stalin's policies in a 'Secret speech'and referred to as 'De-stalinisation'> He believed in a peaceful co-existence ( superpowers could exsist peacefully together)
For a time it was peacful 'thaw' in the cold war > until USSR brutally put down uprising in Hungary

23rd October 1956- Students demonstrated in Budapest, the capital of Hungary, demanding free elections, free press and the withdrawal of Soviet troops. Statue of Stalin was pulled down and dragged through the streets

After demonstrations began in October 1956 Krushchev sent troops and tanks to Budapest to try and restore peace. The tanks opened fire and killed 12 people injuring many more

Krushchev didn't want to seem weak to other memerbs of the Warsaw pact. Aswell as the leader of China Mao Zedong urging him to stand firm against any deviation from communism.

He decided that Nagy had gone too far and on November 4th 200,000 Soviet Troops and 6,000 tanks returned to Hungary

As the crisis was raging in Hungary, world attention was drawn away to events in the Middle East with the Suez Crisis.

The invasion of the British and French troops was a fortunate diversion for Krushchev.

Cause: Berlin Ultimatum: 1958- Krushchev issued the Berlin Ultimatum. He accused allies of breaking Potsdam agreement and said they should leave Berlin within six months.

Cause: Paris summit- 14 May 1960 Krushchev and Eisenhower were due to meet. 9 days before the summit the USSR announced that it had shot down an American U-2 spy plane near the Soviet city of Sverdlovsk. Krushchev demanded an apology from the USA an that all flights should stop. Eisenhower would stop the flights but refuse to give an apology. The summit ended badly with Khrushchev storming out.

Cause: Vienna summit- Krushchev fixed another summit with the new US president John F Kennedy. Krushchev thought he would be able to use his experience to push Kennedy around however Kennedy had re instated the 'Truman Doctrine'. At the summit Krushchev demanded that the Western forces leave West Berlin, Kennedy refused and increased US defense. In July 1961 Krushchev announced that the Soviet Union defense budget would be increased by more than 30%.

Event- 13th August 1961 Krushchev ordered the border closed between East and West Berlin. This began as a wire entanglement of 43km but developed into a wall that was 3.6m high and 1.2m wide. The wall was patrolled by soldiers, dogs, floodlights and trip wires machine guns.

Impact for US-Soviet relations-The construction of the wall did lead to a stand off in October 1961 between the two superpowers, as the USA disputed the right of Soviet troops to patrol and guard checkpoints at the wall. Both sides stationed troops and tanks on either side of the wall.

Impact for Germans- Some East Berliners did manage to escape the wall, by tunneling, swimming or jumping, but escape was rare. Families were split and travel restrictions made it very difficult for reunions. In 1963 Truman visited West Berlin and spoke to a cheering crowd of 200,000, including some East Berliners listening from Beyond the wall.

Between 1949 and 1961 about 4 million East Berliners fled to the West through Berlin as they were dissatisfied with the economic and political conditions. These were often professionals and skilled craftsmen and is sometimes referred to as a 'brain drain'

An attempt to help communist gain support again, by removing it's worst features.

In Czechslovakia demonstrations against the Soviet Union went on until April 1969.

Dubcek was forced to resign by Gustav, he was a strict hard communist

The invasion worsened relations between East and West Germany

A period of detente occurred after the invasion relieving some tension During this time the USA were preoccupied as they were in the middle of an election and the Vietnam war.

Dubcek's reforms encouraged opponents of communism and led to demands for even more radical reforms

The Soviet Union decided to invade because they were worried that Czechslovakia might leave the Warsaw pact as they are one of the most important countries due to its geographical position and its industry.