There's a deeper reason I believe in NATO, and it can be summed up in two words: collective defense. It's the simple notion that if you have Allies, you're less likely to go to war for the wrong reasons. And when you go to war together, after a transparent discussion of the alternatives, you'll have greater power.
One evening in late August, it just so happened that I would get mugged on Massachusetts Avenue around 10pm in front of the Gandhi statue. The entire moment seemed ironic because it was not that late and not a particularly dark spot. The newish Gandhi monument was watching over me so what did I have to be afraid of?