After World War II, tensions arose between the US and Soviet Union due to disagreements over politics and economics, starting the Cold War. President Truman implemented the policy of containment to limit the spread of communism and instead promote democracy. This included the Truman Doctrine, which provided financial aid to countries to prevent them from becoming communist, and the Marshall Plan, which gave $12.5 billion to Western Europe for rebuilding to prevent the spread of communism there.