The Cold War was a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc, which began following World War II. Historians do not fully agree on its starting and ending points, but the period is generally considered to span the 1947 Truman Doctrine (12 March 1947) to the 1991 Dissolution of the Soviet Union (26 December 1991).[1] The term "cold" is used because there was no large-scale fighting directly between the two superpowers, but they each supported major regional conflicts known as proxy wars.