As they signed NATO into being after World War II, its founders fervently believed that only if the West's democracies banded permanently together could they avoid a catastrophic global atomic conflict. Over the 75 years since, the alliance has indeed avoided war with Russia, also becoming a major political, strategic and diplomatic player well beyond its borders. It has survived disagreements between leaders from Eisenhower, Churchill and de Gaulle to Trump, Stoltenberg and Merkel, faced down Kremlin foes from Stalin to Putin and endured unending questions and debate over what new nations might be allowed to join.