Following World War II, the world was in turmoil, with many nations experiencing political unrest. The US government, already wary of communism as a result of George Kennan's Long Telegram, was shocked when a number of nations in Europe and Asia chose communist governments in the late 1940s.
When the UK informed the US that it could no longer afford to fight communist insurgencies in Greece and Turkey, US President Harry S. Truman issued what became known as the Truman Doctrine: a promise that the US would do whatever was necessary, both economically and militarily, to contain the spread of communism around the world.With this move, the United States indicated that its position on the global stage would not stop after WWII, effectively ending a century and a half of isolationist foreign policy in the United States.
During Truman's administration, the Truman Doctrine would lead to another Asian war, this time in Korea, as the US government tried to prevent Korea's unity under a communist government. Truman's strategy would propel American interventions into the 1980s.
The Marshall Strategy
The reconstruction of Europe was one of the most urgent issues in the early wake of World War II. The conflict left a path of devastation that crippled infrastructure and resulted in major food shortages. The US administration was concerned that a starving, ravaged Europe would turn to communism. (as China would do in 1949). To help stabilize the European economy, US Secretary of State George C. Marshall suggested a $13 billion economic assistance package for Europe.
The Marshall Plan was a huge success, assisting in the rehabilitation of European countries that took the assistance. It also helped the American economy because Marshall Plan money were used to buy American products.