The American alarm of Russian expansion in Europe greatly increased when Britain declared on February 24, 1947 that she could no longer give the much-needed financial and military aid to the Greek government which was in danger of being overthrown by the communist guerillas. Another country threatened by Russian-directed communist guerillas was Turkey. America did not have any doubt about the great increase in power which domination over Greece and Turkey would give to Russia. (Both Turkey and Greece had a population composed largely of poor peasants. These two countries were liberated by Anglo-American troops from German control in 1944. After the liberation, the communist guerillas in these two countries threatened to overthrow their governments. 
The communist guerillas received military aid from Yugoslavia and the Soviet Union. The government of Greece received military support from the British government.) See additional information below.
On March 12, 1947, President Truman enunciated the Truman Doctrine. The essence of the Doctrine was that "it must be the policy of the United States to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressure."
This was clearly an anti-communist doctrine. This amounted to an American declaration of war upon Communist Russia. President Truman followed his speech with massive military and economic aid to Greece and Turkey. The communist guerillas were defeated by the American troops in 1948 in both Greece and Turkey.
The U.S. government also realized that a prosperous Europe would be the most effective barrier to Communism. On June 4, 1947, the U.S. Secretary of State, George Marshall, speaking at the Harvard University, stated that, "It is logical that the United States should do whatever it is able to do to assist in the return of normal economic health in the world, without which there can be no political stability and no assured peace." Immediately after the speech the United States invited all European countries to put forward plans for economic reconstruction so that the United States would provide the necessary financial aid to them. The Soviet Union refused to accept the American financial aid. The first reason was that the state which applied for Marshall Aid was required to disclose her economic records to the American government - this was regarded by the Soviet Union as an American interference in the internal affairs of another state. The second reason was that receiving American aid would involve the risk of opening the Soviet Union to western influences which would weaken the totalitarian system of government. In the eyes of the Soviet Union, the United States was giving economic aid to all European countries to make them anti-communist. Shortly after the proclamation of the Marshall Plan, Andrei Zhdanov, one of Stalin's lieutenants, said, "The United States proclaimed a new, frankly predatory and expansionist course.
The purpose of this new frankly expansionist course is to establish the world supremacy of American imperialism. Because of these two reasons, the Soviet Union also forbade her satellite countries (the eastern European countries) to accept Marshall Aid. In 1949, Russia tried to counter the Marshal Plan -by offering financial aid to her satellites under the Molotov Plan.With the proclamation of the Truman Doctrine of March 1947 and the launching of the Marshall Plan, the United States was clearly leading the western nations to resist Russian Communist expansionist activities in Europe. Cold War had begun.
this blog is on the cold war and why it happened and what toke place when it started and how long it lasted and talks about the nuckulare bombs that were droped on countrys and the people that were affected by the cold war.
