Wisconsin Sen. Ron Johnson made a standard hawkish statement on Iran yesterday on Fox News Sunday:

We cannot allow them to have a nuclear weapon, if that means military action, that’s what we’ll end up taking.

This prompted Steven Metz to say this:

Metz and I talked about this briefly on Twitter, and we agree that Johnson is blithely endorsing an illegal war. I wanted to add a few points here. Iran hawks such as Johnson support preventive war against Iran because they are excessively afraid that Iran will eventually acquire nuclear weapons. Because of that fear, they have an entirely unreasonable expectation that those weapons will pose such an intolerable threat to the U.S. and/or Israel that it has to be eliminated by force in advance. Set aside for a moment the small problem that a “preventive” attack on Iran isn’t going to prevent the outcome Iran hawks fear, but rather makes it more likely. Of course, there is no justification for preventive war under international law or the U.N. Charter. Indeed, as Metz points out, it is explicitly prohibited under the Charter. Preventive war is inherently unjust, and there is also no way to reconcile it with the U.N. Charter, but none of this interests Iran hawks.

First, they aren’t interested in international law and norms when this restricts what the U.S. and its allies and clients can do, so it’s fair to say that they don’t care that an attack would be illegal. Some Iran hawks might pay lip service to international law while arguing for an attack, but they will do this by warping the definition of “self-defense” beyond recognition. Preventive war can’t possibly be justified as self-defense, but you can be sure that this is how Iran hawks would present it.

Even if they acknowledge that an attack on Iran violates the Charter, they will simply assert that attacking Iran is a matter of national security and that the law should be ignored in this instance. They can always fall back on saying that “there is no such thing as international law” on the grounds that there is no one that can enforce it against the U.S. Finally, we can always count on them to cite the previous illegal wars that the U.S. has fought in the past as part of their effort to dismiss the importance of a war’s illegality.

In short, Iran hawks probably won’t admit the illegality of an attack on Iran, but if they are forced to admit it they will dismiss it as irrelevant. International law matters to these hawks only insofar as it can be used to justify U.S. actions against other states, and when it gets in the way of this they will ignore it and run roughshod over it. We know this because this is how they have treated international law in every debate over military action over the last two decades.