What are you talking about, 'legitimate targets'? There are no rules who they are allowed to attack and not allowed to attack. 'They' are capable of targeting any man in this country they like. This is why you either make friends with other countries or carry the biggest stick. We're already talking acts of war, it's not like you can increase the backlash any further than a declaration of war.
I think you're forgetting that war is not a board game with a friendly set of rules everyone has implicitly agreed to follow.
If we or someone else who signed that is the one making a strike, sure. But it won't always be.
It could even be a country that signed it, but is aiming for complete dominance, and throws out the rules because they are already at war with the rest of the world anyway.
I think you're forgetting that war is not a board game with a friendly set of rules everyone has implicitly agreed to follow.