From the middle of the 1960s, Czechs and Slovaks showed increasing signs of rejection of the existing regime. This change was reflected by reformist elements within the communist party by installing Alexander Dubček as party leader. Dubček's reforms of the political process inside Czechoslovakia, which he referred to as "Socialism with a human face", did not represent a complete overthrow of the old regime, as was the case in Hungary in 1956. Dubček's changes had broad support from the society, including the working class, but was seen by the Soviet leadership as a threat to their hegemony over other states of the Eastern Bloc and to the very safety of the Soviet Union. Czechoslovakia was in the middle of the defensive line of the Warsaw Pact and its possible defection to the enemy was unacceptable during the Cold War.