The public reacted positively to the reforms
The USSR did not like Dubcek's reforms
The USSR became concerned about Dubcek's commitment to the Warsaw Pact
Dubcek confirmed that Czechoslovakia would remain a loyal ally to the USSR
Brezhnev did not want Dubcek's actions to encourage other satellite states to reform
In the 1960s, the USSR's control over Eastern Europe was not as strong as it had been in the 1940s
Yugoslavia had broken away from the USSR
Romania had refused to attend Warsaw Pact meetings
Brezhnev needed to keep control over Czechoslovakia