In the lead-up to the Truman Doctrine.

The policy of containment was one of the most important policies the US developed. Not only did it suggest to actively seeking to prevent the spread of communism, but also it was also the key aim in "Truman Doctrine"--the Doctrine that veered the US's attitude towards the rest of the world. It said, "it was America's duty to interfere to 'help free peoples to work out their own destiny in their own way'", which abandoned the previous policy, the policy of isolation. How did the allies in the Second World War turn against each other and what caused the USA to abandon its long-term isolation policy?

In February 1945, the Big Three, Stalin, FDR and Churchill, met in Yalta. It was the second time the Big Three ever met. Even though the conference seemed to be successful, much tension had also been created. One of the points they agreed on was to help freed people of Europe set up democratic and self-governing countries by helping them to hold elections, but Stalin later on did not hold any elections in Eastern Europe, and the American press immediately turned hostile towards Russia. This action of Stalin angered the people in Britain and America, thus they realized that Stalin should not be trusted completely. Tension usually was higher when countries mistrusted each other.

In July 1945, the Big Three met again in Potsdam, but two of the Big Three were new, President Truman of America and Prime Minister Attlee of Britain. They did not know what secret deals were agreed on in Yalta Conference, therefore they were a little passive, because Stalin could just make up some deals that were not agreed in Yalta, but they would never know. Stalin, in their eyes, was greedy because he kept asking for more reparations and lands, however Truman and Attlee kept refusing the requests. Both sides were displeased. Unhappiness was always a factor of tension forming.

The most important reason why the policy of containment developed was George Kennan's Long Telegram. George Kennan was the deputy chief of US mission in Moscow and lived in Moscow since 1933, who personally detested Communism, and thus dislike Russia for running by Communists. He claimed that "the Russians were determined to destroy the American way of life, that they had to be stopped, and that the best way to do so was by educating the public against Communism, and by making people wealthy, happy and free."1 Also, it said that Russia is not an ally to be trusted. This alerted the US government. Although Kennan's opinions were very biased, Truman took no notice because he himself hated communism as well. This, later on, helped to develop the policy of containment.

Another important event that made the American determined to interfere the European business was the aggrandizement of the USSR, which created buffer zones, took over the Eastern Europe, and demanded for more. Americans regarded this as a threat to their own ideology, freedom of people and itself. They, more or less, feared the USSR. Therefore they needed to take action to prevent endangering itself, and thus in March 1947, Truman issued the "Truman Doctrine," and the policy of containment officially formed.

Nearly all the events that took place since 1917 contributed some tensions for US deciding to have the policy of containment, but the events that happened in 1945-1946 had more important roles to play for the policy of containment. The establishment of the policy of containment was another symbol of the declaration of the famous Cold War.

1 Clare, John. http://www.johndclare.net/Smartass_ColdWar.htm, Kennan. September 4, 2005.