Basic tenets for making sense of these new rules:
Stop thinking that nations are like people. Nations are like enormous people with very tiny brains that function extremely primitively. Might = right. Money = power. (You can buy friends.) Enemy = inhuman.
If you want to bomb a hospital you can do that if there are bad guys in it.
You can kill women or children if there are bad guys near them.
You can bomb anyone or any target if you immediately claim that you made a mistake. (Say, "sorry". Blame technology.)
You can bomb the sh*t out of your enemy and wipe their nation off the face of the earth if they take an unprovoked aggressive action against you first that made you look weak, unprepared and clueless.
Always prepare for an aggression. You might even foment a large-scale aggression if you are sure that you can convince the majority of your allies that your retaliation or response is in the spirit of self-defense or self-preservation. (Then you are not acting preemptively.) In other words: You can start a war if you can prove that your enemy is about to carry out a preemptive strike.
You can start a war on any country if you can prove that their government is unstable and run by fascists or dictators who are plotting world domination and mistreating their own people.
You may threaten the nuclear option if you are absolutely certain that you are right, morally superior to a fault and have eliminated all other viable options. (It also helps to have God's permission here.)