You cant just go into a country because they have nuclear weapons. We have them, would it be ok for another country to do that to us, or the USA, or France, Pakistan, India, North Korea etc? No, and it would not be tolerated either
I was listening to the radio very early this morning and some "expert" said that this was a war crime, and that the US couldn't claim it was a defensive act because there was no action against the US by Iran. I didn't hear the rest of the discussion, because the thunderstorm stopped and I went back to sleep.
The ICC issuing a warrant for a serving US president would be a first though.