You key onto a very important handicap.
I wrote the rules of engagement for the United Nations when I was in Central America commanding the mission there. It was so boring that I didn't have much else to do. The war was virtually over, and the Contras had been demobilized.
I recommended that the mission be shut down. That was not accepted because there was a large civilian component turning it into their career choice. Subsequently, when it was shut down, it just moved to El Salvador. It's UNOSAL.
It was easy to write them for chapter 6--you know, 30 rounds of ammunition, don't carry your weapon loaded, be neutral, be impartial. Very rarely were you getting shot at. It was normally some out-of-control young soldier who wanted to take on a UN observer or soldier.
Now it's much more complicated, and now countries refuse to let the central agency in New York establish the rules of engagement. Each nation's lawyers, military, and foreign policy people get together and write the rules of engagement, and quite frankly, rarely can they keep up, because the situation changes in the field dramatically. That's when commanders have to earn their pay and adjust them as required. Yes, it's a key issue.
Nobody, but nobody, issued rules of engagement in World War II. You were supposed to kill as many as you could, get them out of the way, and recapture the territory. Today it would be politically incorrect to establish or to issue a rule of engagement like that.
For soldiers it's very frustrating, and ever more shall be so, I imagine, because I don't think any nation will subordinate itself to UN rules of engagement or NATO rules of engagement again.