I have to agree that a nuclear Iran is a scarey thought but I'm not sure what we can do about it.

Even if we stop them with force now, it will only drive them to want them more and probably convince other nations to do the same before the US has a chance to try and stop them with force.

If we resort to force with the attitude that we can ignore international law when we're sufficiently scared, then isn't that playing into the very thinking we would accuse them of?

We cannot stop others from gaining such weapons indefinitely. Anything we do to stop it now will only delay the inevitable. In light of that, I think it would be better to figure out how we are going to deal with the inevitable sooner than later.