sentences:  The Reagan Doctrine followed in the tradition of U.S. presidents developing foreign policy "doctrines", which were designed to reflect challenges facing international relations, and to propose foreign policy solutions.The practice began with the Monroe Doctrine in 1823, and continued with the Roosevelt Corollary, sometimes called the Roosevelt Doctrine, introduced by Theodore Roosevelt in 1904.The post–World War II tradition of Presidential doctrines started with the Truman Doctrine in 1947, under which the US provided support to the governments of Greece and Turkey as part of a Cold War strategy to keep both nations out of the Soviet sphere of influence.