In 1955, Moscow invited Syria, along with Egypt, to join a pro-Soviet pact. Turkey, a U.S. ally, mobilized troops along its southern border in an attempt to dissuade Syria from joining this pact. Soviet Foreign Minister Vyacheslav Molotov threatened Turkey not to use force against Syria, prompting Ankara to back down. The Syria-Soviet relationship was soon cemented. From 1955 to 1960, Soviet Premier Nikita Khrushchev provided Syria with more than $200 million in military aid to solidify the alliance and to counter U.S. influence in the region.
Source: The Syria-Soviet Alliance – Jewish Policy Center – Spring 2009.