The Soviet Union saw Cuba as a key strategic problem: the USA had missiles close to the Soviet Union, but the Soviet Union had no missiles close to the USA.
Brezhnev’s response to Dubček’s reforms was to invade Czechoslovakia because he could not allow any weakness in control, even if it wasn’t Dubček’s intention.
President Kennedy and his team considered different options, with some advisers (the ‘hawks’) wanting to attack straight away, while others (the ‘doves’) wanted to avoid nuclear war if at all possible.
The Soviet Union declared the right to invade any Eastern bloc country that was threatening the security of the Eastern bloc as a whole after the Soviet invasion of Czechoslovakia.
The Soviet invasion of Czechoslovakia was important to Soviet control of Eastern Europe because it showed that the Soviet Union would invade any country that threatened the security of the Eastern bloc.
Yugoslavia and Romania also backed off from the Soviet Union, weakening the Soviet Union’s grip on Eastern Europe after the Soviet invasion of Czechoslovakia.
The Soviet invasion of Czechoslovakia was important because the Brezhnev Doctrine meant that the Soviet Union reserved the right to invade any country that threatened the security of the Eastern bloc.
Western European communist parties were horrified and declared themselves independent from the Soviet Communist Party after the Soviet invasion of Czechoslovakia.