The Soviet Union used their diplomatic and economic influence, backed up by the threat of military force to dominate the internal politics of their satellite states. 1964 was a bit of a turning point, as it marked the beginning of Leonid Brezhnev's tenure as Soviet leader. He made intervention in eastern Europe to "protect" communism a matter of official foreign policy doctrine, as he demonstrated in crushing the Prague Spring in 1968. Much happened between 1945 and 1964, however, and it is safe to say that this was the period where eastern Europe was the primary focus of Cold War hostilities, especially in Germany. After 1964, and really after the Berlin and Cuban Missile Crises, the US and Soviet Union shifted their attention elsewhere.