The Eisenhower Doctrine of 1957 declared that the United States would distribute economic and military aid and, if necessary, use military force to stop the spread of communism in the Middle East. Eisenhower found it difficult to convince leading Arab states or Israel to endorse the doctrine's purpose or usefulness. Nonetheless, he applied the doctrine in 1957-58 by dispensing economic aid to shore up the Kingdom of Jordan, by encouraging Syria's neighbors to consider military operations against it, and by sending U.S. troops into Lebanon to prevent a radical revolution from sweeping over that country. The doctrine consisted of a major commitment by the United States to the security and stability of the Middle East and signaled a new level of U.S. resolve to exert influence in international affairs. By issuing the doctrine, Eisenhower raised the prospect that the United States would fight in the Middle East and accepted responsibilities in the region that the United States would retain for decades to come.