Russian President Vladimir Putin has made it well known his antipathy towards NATO, claiming the Alliance took advantage of Russian weakness after the collapse of the Soviet Union in violation of promises allegedly made to Moscow by Western leaders. Steven Pifer argues that no such promises were made, a point now confirmed by someone who should know: Mikhail Gorbachev, former president of the Soviet Union.
Source: Did NATO Promise Not to Enlarge? Gorbachev Says “No” | Brookings


