Of course, a more obvious answer - and one more in keeping with the principles and Constitution of the US - is keep out of places we have no business being.
I don't remember the "don't go to war with Iraq" clause of the constitution. Is that in Article II or II?
I have no trouble having a serious discussion with you about whether the Iraq war was reasonably necessary for the self-defense of the US. I believe it was. You believe (I suspect) it was not.
The standard Buchananite argument here is that everyone would leave us alone if we just left them alone. So the best self-defense, they argue, is to bring all our troops home. That is a serious public policy argument--I think it is wrong but not silly. But it is a public policy argument about how best to defend our country. It is NOT a constitutional argument.
To argue that the constitution forbids our congress and president and the vast bulk of the american people from acting in what they believe is self-defense is just silly.