You have to realize Iraq was already warned that if it does anything premptively, all hell would come down.
Yeah, I know, and Iraq probably won't be able to do that much with warning -- but this is a habit the U.S. is developing. And all of the machinations at the U.N. do not help the problem one bit.
And at some point there will be an enemy who is both wiley enough and capable enough to do us a world of hurt because we are required, by world and internal public opinion, to be so transparent about our military actions (particularly our offensive actions).