I am well aware of what the US has signed and not signed; I am well aware of what the EU-NATO states have signed and not signed; and I am well aware of the ICRC and what it has recommended - and what of that has been accepted or rejected by various states.

I have also frankly stated (and linked to) the US legal academics who dispute the basic rules adopted by the Bush Administration and expanded in the targeted killing area by the Obama Administration - and where the Legistative and Judicial branches have endorsed those rules.

Mere citation of the UN Charter and North Atlantic Treaty are inadequate to shake my boots. I know and have frankly admitted the divide between the USG position and the dominant EU-NATO position - in this and in other jus ad bellum and jus in bello issues. That divide cannot be bridged without one side or the other substantially changing material beliefs.

I'm serious too. If what you call "even formal allies" truly believe what you apparently believe about the US, then they would have a moral and ethical duty to terminate the alliances - and, also legal obligations to do that under both the UN Charter and North Atlantic Treaty (if they interpret them as you do). If some of them elect to do that, I would not blink.

Whether you want to charge some or many USAians with War Crimes is up to you. If you believe that, you should say so. Put the meat on the table.

As to sovereignty, you allege:

You see, there's a thing called sovereignty, and claiming this for the own country while ignoring the sovereignty of other countries with violent actions on their home turf is disrespectful and arrogant.
and I know that's not directed at me - unless you've disregarded everything I've written here and elsewhere.

When State A relies on a neutrality law argument to justify an attack against an enemy group X within the bounds of State B, State A runs the risk that State B will respond with something other than silence, a diplomatic protest or a claim for money. That is the answer to your questions:

How would you react if Cuba did assassinate some exile Cubans in Florida with their marines for being terrorists?

Would you want the Russian air force to bomb a motel in Kansas because an exile Chechen leader sleeps there?

How about an accidental bombing of a wedding party in Arizona because the Mexicans suspected a drug crime lord / terrorist there?
If our Homeland Security would react as it should, we would kill the Cubans, Russians and Mexicans. The Chinese and Russians would do the same thing.

What would the EU-NATO states do in the same three situations - make the US the attacker and change the locations to UK, France and Germany ?