We might agree that Russia’s incursion into the Ukraine, while regrettable, doesn’t concern us. But if Vladimir Putin did the same thing to Estonia, another bordering country with a large and complaining Russian minority, we would be at war. That’s because Estonia and the other Baltic Republics are members of the North Atlantic Treaty Organization (NATO). The members of that organization, founded to deter the Soviet Union, have a pact that an attack on one member nation is an attack on them all, and that they will all go to war against the attacker. Tomorrow a NATO summit begins, and it’s being hailed as the most important since the end of the Cold War.