The Reagan Doctrine was a policy during the presidency of Ronald Reagan (1981-1989). It was meant to help anti-communist groups around the world. In the Cold War, the U.S. and Russia were on opposite sides of a big argument. They were enemies, and the Reagan Doctrine was meant to help the U.S. win the fight. The policy was to give money and weapons to groups fighting against communism in different countries. The main idea was to stop communism from spreading to other countries.