A historical look at NATO and its many challenges as Biden heads to summit on Ukraine

As President Biden travels to Belgium to meet with NATO members about the war in Ukraine, he says the alliance is more united today than ever. The reason: Vladimir Putin. 

NATO has never faced a test like this — a hot war in Europe that carries the threat of biological, chemical or even nuclear weapons. Though NATO is not defending a member nation, it has grown unified defending everything the alliance was created to preserve. 

NATO grew out of World War II as a defensive alliance to shield Western Europe from the Soviet Union. America and Europe also wanted to contain Germany, the aggressor nation in both World Wars.