I believe the US is morally justified in doing whatever it takes to stop nK and Iran - but I would bet no more than 5% of Americans agree, because 'whatever it takes' is pretty violent.
If we don't have the stomach for that (and we don't), then we need to decide how we are going to live with a "pistol pointed at [our] head 24/7".
It's also unnecessary, as there are other -- and better -- ways to do this. Bush has made a significant point of drawing a distinction between the NK regime, and the people of NK. He did it again, today.
The key to the problem is not to destroy the people, it's to destroy the regime. I'm pretty sure we have the stomach to do that, and with China we have a partner (not an ally) with an incentive to finally address the problem of that little bedbug next door.
To a man with a hammer, the whole world is a nail. Put down the hammer, and put on your thinking cap.