There are some well meaning, but VERY misguided comments in this thread.
In case some of you might have missed, NukeCop is a serving member of the Armed Forces. In this case, I believe he (or she) is asking the question in a rhetorical sense, and without the intent to seek guidance in the commission of an act which is unlawful under the present circumstances.
You see, in addition to the laws of the host nation, NukeCop is also under the provisions and jurisdiction of the Uniform Code of Military Justice--as long as he (or she) carries the identification card of a servicemember.
First, the three General Orders under which servicemembers perform duties as Sentinels of the Guard are specific:
1. I will guard everything within the limits of my post, and quit my post only when properly relieved.
2. I will obey my special orders, and perform all my duties in a military manner.
3. I will report violations of my special orders, emergencies, and anything not covered in my instructions to the Commander of the Relief.
Different branches have different wording and length, but the intent is still the same. Thus, if the special orders for NukeCop's post call for warning shots, and then shots directed at the pelvic area, he (or she) had damned well better do EXACTLY that--and NOTHING ELSE.
Should he (or she) make the decision to step outside the boundaries of the special orders, this is what they might face:
...(1) In that you did, while assigned as a Sentinel of the Guard at Post XXX, failed to follow your Special Orders, of which you had prior knowledge, to wit: fire warning shots to discourage a breach of your post. This is in violation of Article 92(2), UCMJ.
...(2) In that you did, while assigned as a Sentinel of the Guard at Post XXX, failed to follow your Special Orders, of which you had prior knowledge, to wit: to fire aimed shots at the lower body/pelvic area to stop or disable an intruder. This is in violation of Article 92(2), UCMJ.
...(3) In that you did, while assigned as a Sentinel of the Guard at Post XXX, did commit the act of Murder, by intentionally discharging your assigned weapon at the chest area of XXXXX, thus causing death as a direct result of your actions. This is in violation of Article 118, UCMJ.
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If they find in Courts-Martial that NukeCop intended to kill the intruder, guess what the penalty is? It involves being the target at a high-power match.