Wasn’t this a big pantomime?
Gorbachev was pushing ahead with Glasnost, but meeting resistance particularly from top brass within the military, the story goes that his team colluded with the West to let this guy infiltrate Soviet airspace, at a given time when there were certain events going on, including the Moscow radar being down for repairs.
The subsequent sackings of top military leaders for their incompetence paved the way for reforms with the west.
Guess the truth will out one day