Just by wearing a uniform troops/military personnel often become targets even in allied countries. Example :- British troops were repeatedly targeted in West Germany by Irish Republican terrorists. British troops stationed in sleepy Gibraltar also targeted by an IRA hit team. Shooting people on there day off, in a safe area is a time honoured terrorist tactic. They don't want a stand-up fight they just want to kill and maim. Chilled out and off guard troops is how terrorists prefer them.