MOSCOW, FEB. 12 -- The Soviet Union announced today that on April 1 it would dissolve the Warsaw Pact, the military alliance with Eastern Europe that was born in the Cold War, protected Kremlin orthodoxy and crushed liberal reform movements in Budapest and Prague.

Since the countries of Eastern Europe broke away, one by one, from the Soviet sphere of influence in 1989, and the Kremlin spoke of the end of the Cold War with the West, the collapse of the Warsaw Pact has been considered inevitable.

Soviet President Mikhail Gorbachev's spokesman, Vitaly Ignatenko, joked with reporters that April 1 "will be more than just April Fool's Day." He said the six countries in the 35-year-old pact "have concluded that the time has come to take steps to wind up the military structure of the organization."

Hungarian Prime Minister Jozsef Antall said the foreign and defense ministers of the Warsaw Pact countries will meet in Budapest Feb. 25 to make the agreement formal. "This will be a historic moment in the life of the nation," Antall said.

The Warsaw Pact, which had 5 million troops and ensured Moscow's dominion throughout the East Bloc, began May 14, 1955, as a response to West Germany's entrance into NATO. It also served as the Kremlin's ideological police force, making sure that Moscow's Communist Party was the de facto ruler throughout the bloc.

Until the democratic revolutions in Eastern Europe began in 1989, the confrontation between the Warsaw Pact and NATO dominated world politics. But at last year's European summit meeting in Paris, leaders of NATO and Warsaw Pact countries signed a treaty declaring that they were no longer enemies. And last month, the Czechoslovak Federal Assembly asked the government to dissolve the Warsaw Pact.

Soviet officials still speak vaguely of the Warsaw Pact continuing to exist in some political or economic capacity, but it is clear that such discussions are not always taken seriously here and in East European capitals.

Czechoslovak President Vaclav Havel said he expected that Prague would actually cooperate more closely with NATO in the future, saying the Western military alliance is the only international body in Europe that follows democratic rules.

The former Eastern Bloc's agreement to end the military alliance apparently will come as its trade body, Comecon, is also terminated. Comecon leaders are expected to meet in Budapest at the end of the month.

Hungary and Czechoslovakia, which saw reform movements in their countries crushed by Soviet tanks in 1956 and 1968 respectively, were especially active in trying to wind down the Warsaw Pact as quickly as possible after their revolutions in 1989. After months of lobbying Moscow, Budapest and Prague received letters from Gorbachev this week informing them of Moscow's willingness to use April 1 as the date for dismantling the pact.

Ignatenko said Moscow hopes that NATO will respond to the Warsaw Pact announcement. But in Brussels, a NATO spokesman told Reuters that the alliance did not feel compelled to respond in kind.

"It's up to the member states of the Warsaw Treaty organization to decide on their own future security policy and the relevance of {the pact} in this regard," the spokesman said.