How do you “murder” military personnel supporting combat missions in a war zone?
First you have to classify uninvited foreign military personnel protecting the people stealing oil in an oil zone as military personnel supporting combat missions in a war zone.
Second, you need to have personnel who are not members of the uniformed services of a recognized nation, and not eligible to be treated as combatants, fire a peacekeeper rocket at the oil thief protectors. The warlike act of a unprivileged non-combatant would qualify as the simple civilian crime of murder.
I would say there's a better than even chance that the "murder" of those three U.S. military personnel involved a U.S. drone that either: (1) malfunctioned and accidentally crashed inside the perimeter of the U.S. base in Jordan, or (2) was hacked by adversaries who were able to gain control over it and guide it.