I’ll say losing its protection is an over-simplification. Yes, when a significant military target is misusing the protected signs they can be ignored. You still however are not allowed to break the first rules around minimising any civilian losses. So the civilian people in the area are still protected, they don’t lose their protection. Injuries to civilians should always be kept minimal. If the hospital is cleared out and is only used for military operations (treating wonder soldiers is not a military operation here) then the symbols of the hospital don’t have any protection. No, if you attach from within anything that is protected, you should expect to be attacked. At the same time, any attack on the enemy has to be proportional and should always strive to minimize civilian losses. Including civilian material losses. An example is a sniper hiding in a civilian building. It’s probably a war crime to bomb the house. Even when there are no civilians in the house. If there is a full platoon using the same place for defense, and the terrain is hard, it is probably ok for the same bombing. If the building also has a few hundred civilians, well it is back in the probable war crimes to bomb it out and some other ways of taking the objective have to be considered. This even looks at the house without any special protection. Same with an ambulance, if there are enemy combatants in the ambulance attacking you, of course, you can take it out. If there are enemy combatants in the ambulance that are not attacking you, you can take them prisoner. But you can’t shoot first to make sure there are no combatants in it. For me, if there has been a bombing of a hospital building with masses of patients inside, it’s a clear war crime. Even if there were a few military in the same building.