The 'Long Telegram' was sent by George Kennan from the United States Embassy in Moscow to Washington, where it was received on February 22nd, 1946. The telegram was prompted by US inquiries about Soviet behavior, especially with regards to their refusal to join the newly created World Bank and International Monetary Fund. In his text, Kennan outlined Soviet belief and practice and proposed the policy of 'containment,' making the telegram a key document in the history of the Cold War. The name 'long' derives from the telegram's 8000-word length.
US and Soviet Division
The US and USSR had recently fought as allies, across Europe in the battle to defeat Nazi Germany, and in Asia to defeat Japan. US supplies, including trucks, had helped the Soviets weather the storm of Nazi attacks and then push them right back to Berlin. But this was a marriage from purely one situation, and when the war was over, the two new superpowers regarded each other warily. The US was a democratic nation helping put Western Europe back into economic shape. The USSR was a murderous dictatorship under Stalin, and they occupied a swathe of Eastern Europe and wished to turn it into a series of buffer, vassal states. The US and the USSR seemed very much opposed.
The US thus wanted to know what Stalin and his regime were doing, which was why they asked Kennan what he knew. The USSR would join the UN, and would make cynical overtures about joining NATO, but as the 'Iron Curtain' fell on Eastern Europe, the US realized they now shared the world with a huge, powerful and anti-democratic rival.
Kennan's Long Telegram didn't just reply with insight into the Soviets. It coined the theory of containment, a way of dealing with the Soviets. For Kennan, if one nation became communist, it would apply pressure on its neighbors and they too might become communist. Hadn't Russia now spread to the east of Europe? Weren't communists working in China? Weren't France and Italy still raw after their wartime experiences and looking towards communism? It was feared that, if Soviet expansionism was left unchecked, it would spread over great areas of the globe.
The answer was containment. The US should move to help countries at risk from communism by propping them up with the economic, political, military, and cultural aid they needed to stay out of the Soviet sphere. After the telegram was shared around government, Kennan made it public. President Truman adopted the containment policy in his Truman Doctrine and sent the US to counter Soviet actions. In 1947, the CIA spent considerable sums of money to ensure the Christian Democrats defeated the Communist Party in elections, and, therefore, kept the country away from the Soviets.
Of course, containment was soon twisted. In order to keep nations away from the communist bloc, the US supported some terrible governments, and engineered the fall of democratically elected socialist ones. Containment remained US policy throughout the Cold War, ending in 1991, but discussed as something to be reborn when it came to US rivals ever since.