Following the Iran crisis of 1946, Harry S. Truman declared what became known as the Truman Doctrine in 1947, promising to contribute financial aid to the Greek government during its Civil War and to Turkey following World War II, in the hope that this would impede the advancement of Communism into Western Europe. Later that year, diplomat George Kennan wrote an article in "Foreign Affairs" magazine that became known as the "X Article", which first articulated the policy of containment, arguing that the further spread of Communism to countries outside a "buffer zone" around the USSR, even if it happened via democratic elections, was unacceptable and a threat to U.S. national security. Kennan was also involved, along with others in the Truman administration, in creating the Marshall Plan, which also began in 1947, to give aid to the countries of Western Europe (along with Greece and Turkey), in large part with the hope of keeping them from falling under Soviet domination.