Ideology, security fears, economic aims and mistrust turned the wartime alliance into rivalry by 1947.
The USA and the USSR fought together against Nazi Germany, but they were allies of necessity. Once Germany was defeated in May 1945, the reason for cooperation weakened and older differences returned.
Ideology divided them. The USA believed in liberal democracy and free-market capitalism. The USSR was a one-party communist state that expected capitalism to collapse. Each saw the other's system as a long-term threat.
Security fears pulled them apart. The USSR had lost around 27 million people and been invaded through Eastern Europe twice in thirty years. Stalin wanted friendly governments on his western border. The USA, with the atomic bomb and a strong economy, wanted a world where such spheres did not block open trade and free elections.
Economic aims differed. The USA wanted an open world economy and the recovery of Western Europe, including Germany. The USSR wanted reparations from Germany to rebuild. Wartime grievances deepened mistrust. Stalin resented the delay in opening a second front until June 1944, and the abrupt cutback of Lend-Lease aid in May 1945.
Leaders mattered too. Roosevelt had hoped to manage Stalin through personal diplomacy. After his death in April 1945, Truman took a firmer line. Each side read the other's defensive moves as signs of aggression, and this mutual misperception turned disagreements into a rivalry.
- Soviet war dead
- Around 27 million people.
- Second front
- Opened in France only in June 1944, a Soviet grievance.
- Roosevelt dies
- April 1945; Truman takes a firmer line.
Worked example: Weighing causes in an essay-style judgement
You are asked whether ideology was the main cause of the Cold War.
- Ideology explains why each side distrusted the other's long-term aims.
- Security explains specific actions, such as Soviet control of Poland.
- Link them: ideology shaped how each side interpreted the other's security moves.
- Judgement: security fears drove early actions, while ideology made compromise much harder.
Watch out for this
The Cold War started because the USSR wanted to spread communism across the world.
That is one interpretation. Many historians argue Soviet actions in 1945-47 were driven mainly by security in Eastern Europe, and that US actions also contributed.
Check your understanding
Why did Stalin insist on friendly governments in Eastern Europe?
- He saw the region as a buffer against another invasion from the west.
- He wanted access to Atlantic ports.
- The USA had asked him to occupy the region.