The article is focused on Soviet efforts to deploy their forces in Czechoslovakia, which began already in the 1950s. From the early 1960s, Soviet pressure greatly intensified in this direction.
During the spring and summer months of 1968, the Soviet Union made three "peaceful" attempts to place its troops in Czechoslovakia. When this failed, the Soviet Army launched Operation Danube, namely the occupation of Czechoslovakia by Warsaw Pact armed forces.