The correct answer to this open question is the following.
The United States helped countries threatened by totalitarian regimes by applying the Truman Doctrine.
Due to the critical situation in Greece and Turkey in 1947 and the fact that Great Britain said it couldn't keep supporting the country, US President Harry S. Truman created what is known as the Truman Doctrine in order to help nations under the threat of Communism and totalitarian governments. Truman asked the US Congress for $400 million to help to send military support and economic support to those nations.