Yugoslavia was trying (and failing) to sit in both chairs at the same time, same like Serbia is doing today between Russia and the west. You seem extremely uninformed about the subject. The reason why the breakup began after the fall of Soviet Union is because Soviet Union would provide a big support to JNA in case of any unrest, and any effort at seperation would be ended quickly. HVO and other militaries only had a chance after the Soviets were out of the picture.