https://ihl-databases.icrc.org/en/customary-ihl/v1/rule28
> Rule 28. Medical units exclusively assigned to medical purposes must be respected and protected in all circumstances. They lose their protection if they are being used, outside their humanitarian function, to commit acts harmful to the enemy.
> According to the Commentary on the First Geneva Convention, examples of acts harmful to the enemy include the use of medical units to shelter able-bodied combatants, to store arms or munitions, as a military observation post or as a shield for military action.