The Truman Doctrine was a promise passed by president Truman that stated that the United States would help countries battling communism. The Marshall Plan promised to help western European countries rebuild after WWII.
USSR did not agree with either of these promises. Because the Soviet Union was a communist country, it disagreed with the Truman Doctrine's idea of battling communism. USSR also wanted western European countries to remain weak after the war so that the Soviet Union could easily influence these countries. The Marshall Plan halted the USSR's hopes of this happening.
