Everybody always trots out WW2, the "good" war, as the pinnacle example of US foreign policy, the ultimate justification of our right to use force regardless of international law. Forgetting, of course, that the UN was created in response to WW2.
Clearly, WW2 is an anachronism, an example of a type of warfare that history has thankfully buried.
And what kinds of military actions has the US undergone since WW2: Vietnam, Panama, Greneda, and Iraq 1&2? Do you believe that these are the same types of conflicts as WW2? What in these conflicts justified the use of force? What in Iraq justified the use of white phosphorus? Hell, in the Vietnam war, force didn't even work. Not to mention, in Korea, Vietnam, and the Iraq war, there have been plans drawn up to prepare for the use of nuclear weapons. What justifies that kind of force?