No, but my dad did. He was taking some shore leave on an island in the Pacific in 1946. He was in the 1st Cav, and they had to bring their guns with them to the beach (just incase).
It turns out that on an island right next to theirs, there were some Japanese troops. I guess that they either didn't know that the war was over, or didn't care, but they got into their jeep and started shooting at my dad and the other troops. My dad took a few shots, and eventually hit the gas tank (or something explosive anyway).
He was later a guard for the Emperor of Japan during US occupation. A guy charged the gate in a car, but my dad didn't shoot him, just subdued him and took him in.
He was told that if that ever happened again, and he *didn't* kill the guy, he'd be in big trouble.