Truman’s presidency was largely defined by World War II and its consequences. He was a keen promoter of the founding of the United Nations, and in 1948 he signed the Marshall Plan for the rebuilding of Europe. In the same year, Truman ended the blockade of Berlin by the Soviet Union with an air bridge, thereby supplying the city with the necessities of life. The Truman Doctrine marked the start of the Cold War from the Western side.