Under Khrushchev following Stalin's death, the Soviet Union underwent a period of de-Stalinization and attempted to promote a more moderate form of socialism. Khrushchev established the Warsaw Pact in response to NATO but also tried to give satellite states more autonomy. However, reformist movements in Poland, Hungary, and Czechoslovakia were met with force when they pushed boundaries or threatened Soviet control. The Soviet Union also competed more aggressively with the US globally while tensions escalated over Berlin, culminating in the construction of the Berlin Wall.