Why did the United States adopt a policy of containment?

The term containment, introduced by the Truman Administration, describes the foreign policy pursued by the United States after the Second World War. The policy itself was an attempt to 'contain' the Soviet Union within its current borders and frustrate any attempts of expansion. George F. Kennan, a diplomat and US State department advisor on Soviet affairs, introduced the term in his famous Anonymous X - article. Keenan suggested a ' Long term, patient but firm …

…This was the first example of containment as US foreign Policy and also stated the intensions of the United States towards Soviet Union. Although containment was never carried out exactly how George Kennan devised the policy, it was effective when first introduced through the Truman Doctrine and Marshall Plan. It halted the expansion of communism within European states such as Greece and Turkey and also gave the U.S. strategic advantages over the Soviet Union.