The Soviet Union is not dead, it is just in hibernation. Their economy was crap, they had to do something to get it back in gear. What better way than to break up, let the west modernize your former states militaries, pay you money to help your farmers and industries, then when everyone is strong again, come back together.

That is what was planned all along, I think their plans broke apart though because too many of the former soviet states are enjoying their new found wealth and freedom.