Czechs Mark Anniversary of ’68 Invasion : Warsaw Pact: Citizens for first time freely commemorate 1968 assault that ended ‘Prague Spring’ of liberalization.

Sirens howled today to commemorate the 1968 Warsaw Pact invasion on the first anniversary that Czechoslovaks were able to mark without fear of police retaliation.

In Prague, Mayor Jaroslav Koran honored seven Soviets who protested the invasion that ended the “Prague Spring” of liberalization and replaced it with more than two decades of hard-line communism.

Making the Soviets honorary Prague citizens, Koran told them their demonstration in Moscow’s Red Square on Aug. 25, 1968, “salvaged the conscience of their silent country.”

“They protested against the . . . shameful treason committed by the tyrants of the day on a small friendly country,” Koran declared.

The mayor, acting on a City Council declaration last week, also formally stripped Soviet dictator Josef Stalin of honorary citizenship, along with Czechoslovakia’s first Communist president and Gustav Husak, the Communist Party leader installed by Moscow in the wake of the invasion.

Present at the ceremonies was Yelena Bonner, the widow of Soviet dissident Andrei D. Sakharov, who criticized the invasion.

Bestowing the keys of the city to Bonner, Koran declared: “She’s always had the key to our hearts.”

Among the dignitaries gathered for the ceremony at City Hall were Soviet Ambassador Boris Pankin and Alexander Dubcek, the reformist Communist Party leader who engineered the 1968 reforms only to see them crushed by the invading tanks.

Dubcek, 69, who came back from years of official disgrace to become speaker of the nation’s first free Parliament since 1948, chatted affably with Pankin. Their rapport was a striking example of the new reality in Eastern Europe, where democracies have replaced monolithic Communist rule in many countries.

Earlier today a T-55 tank appeared in Wenceslas Square, where weeping Czechoslovaks pelted Soviet armor with rocks and garbage 22 years ago. This time, spectators cheered. The Soviet-made tank was tipped onto its side by a crane and will be left standing through Sept. 6.