When Leonid Brezhnev came to power in 1964, the Soviet empire consisted of Cuba and six reliable satellites in Eastern Europe, the bloc was dominated politically and economically by the Soviet Union, and East–West interactions were kept to a minimum. Soviet military capabilities at this time, moreover, were clearly inferior to the military power of the West. And while East–West relations were testy, they had improved in the aftermath of the Partial Test Ban Treaty of 1963.