Explain why the wartime alliance between the United States and the Soviet Union broke down into hostility after the Second World War

What this dot point is asking

This dot point asks you to explain why the United States and the Soviet Union, who had been allies fighting together against Germany, became bitter enemies after the Second World War. This is the start of the Cold War, a long rivalry that did not involve the two superpowers fighting each other directly but kept the world tense for decades. You should be able to explain the main reasons for the breakdown: their opposite beliefs, their quarrel over the future of Eastern Europe, and the loss of the common enemy that had held them together. The key idea is that the alliance had always been one of convenience, and once the shared enemy was gone, deep differences pulled the two sides apart.

The answer

Allies only against a common enemy

During the Second World War, the United States and the Soviet Union fought on the same side against Nazi Germany. But this alliance was never built on friendship or shared values. It was an alliance of convenience: they cooperated because they had a common enemy. The two countries had completely different beliefs and had distrusted each other before the war. Once Germany was defeated and the common enemy was gone, there was little to hold them together, and their deep differences quickly came to the surface.

Opposite beliefs: capitalism and communism

The most basic reason for the breakdown was that the two superpowers believed in opposite systems. The United States was capitalist and democratic: it believed in private business, free markets, and elections with more than one party. The Soviet Union was communist: it believed in state control of the economy and rule by a single Communist Party. Each side thought its own system was right and feared and distrusted the other. The Americans feared the spread of communism, while the Soviets feared the power of the capitalist West. These opposite beliefs made genuine trust very difficult.

The quarrel over Eastern Europe

The sharpest disagreement was over the future of Eastern Europe, the countries between Germany and the Soviet Union. The Soviet Union had been invaded through this region and had suffered terribly in the war. Stalin wanted friendly, communist governments in these countries to act as a protective buffer against any future attack. To the Soviets, this was about security. But to the United States and Britain, it looked like the Soviet Union was forcing communism on free nations and breaking promises to allow them free elections. This quarrel turned suspicion into open hostility.

Distrust at the wartime conferences

As the war ended, the leaders of the main allies met at conferences to plan the postwar world. At first they managed to agree on some things, but as time went on the meetings revealed how far apart they were, especially over Eastern Europe and the future of Germany. Promises made at these meetings, such as allowing free elections in Eastern Europe, were not kept in the way the West expected. Each side came to feel that the other could not be trusted to keep its word, deepening the suspicion between them.

From suspicion to Cold War

By 1946 and 1947, the wartime friendship had collapsed into open rivalry. The West spoke of an "iron curtain" dividing Europe, with the communist East cut off from the free West. The Soviet Union, for its part, accused the West of trying to encircle and threaten it. Neither side wanted another full-scale war so soon after the last one, so instead of fighting directly they competed in every other way, through propaganda, spying, alliances and influence around the world. This tense rivalry, stopping short of direct war between the two, is what we call the Cold War.

Examples in context

Example 1. The "iron curtain". A leading Western statesman warned that an "iron curtain" had descended across Europe, dividing the communist East from the free West. The phrase captured the new reality: Europe was splitting into two hostile halves. It became one of the most famous descriptions of the early Cold War and showed how quickly wartime allies had come to see each other as enemies.

Example 2. Broken promises over elections. At the wartime conferences, the Soviet Union promised to allow free elections in the countries of Eastern Europe. In practice, communist governments friendly to Moscow were installed instead. To the West this looked like a clear breaking of promises, and it convinced Western leaders that Stalin could not be trusted, which is exactly the kind of distrust that fuelled the Cold War.

Try this

• Cue. Explain why the wartime alliance is described as an "alliance of convenience" and what changed when Germany was defeated.

• Cue. Explain the difference between capitalism and communism and why this made the superpowers distrust each other.

• Cue. Explain why the quarrel over Eastern Europe looked like security to Stalin but like aggression to the West.