The fundamental disagreement at the beginning of the Cold War involved the question of who would control postwar
Europe. The Soviet Union first learned of the American atomic bomb through the use of espionage. George Kennan's "containment"
policy proposed American vigilance regarding Soviet expansionist tendencies. The Truman Doctrine was developed as a response
to problems in greece. The Truman Doctrine marked an informal declaration of war against the U.S.S.R. The Marshall Plan proposed
the infusion of massive amounts of American capital in Western Europe. Overall, the Marshall Plan generated a broad industrial
recovery in Western Europe. The North Atlantic Treaty Organization represented a departure from traditional American isolationism.
NATO intensified Soviet fears of the West. Truman's handling of the Berlin Blockade was an important factor in his victory
in the election of 1948.