And?
Marines do the jobs no one else can, could, or even should do. If that means dying, so be it.
If they are going in there "heavily armed", bet your ass that there won't be a full magazine left if their position gets over-run. Regardless of RoE.
Don’t make me laugh. Marines take their orders from the Ambassador, not the Marine commander. And most Ambassadors that I have met and worked for will not under any circumstance order them to fire.