As Russian tanks roll into Ukraine in the first invasion by a world power against a sovereign European nation since World War II, the world is watching helplessly.

We should have seen this coming, not just in the past six months, but for the past 16 years. Russian President Vladimir Putin’s increasing level of aggression has long been apparent. In 2005, Putin stated that the collapse of the Soviet Union “was the greatest geopolitical catastrophe of the century.” In the years after, he has invaded and attacked one former Soviet republic after another: some with cyberweapons and others with brute force. These earlier invasions were a test to gauge reaction if Putin decided to take more offensive action.