In many ways, Russia’s current defiant geopolitical stance can be traced to a decisive moment in recent history: the belief that the West broke its promises not to expand the North Atlantic Treaty Organization eastwards. But experts argue over what exactly was promised, NATO itself calls the story of the broken promise a “myth,” and the former Soviet president, Mikhail Gorbachev, who is critical of NATO expansion, has said the West kept all its binding commitments following from the reunification of Germany.