Odds are if a fighter is close enough for a pistol then the fighters were committing war crimes by shooting parachuting aviators. The Japanese were known for shooting down parachutes.
What I've learned about "war crimes" is that it doesn't matter what you do as long as you don't lose. And if you win you get to punish the loser for their war crimes and pretend like you didn't commit any.
They're moving pretty quickly relative to you. By the time they realize you've shot at them, they'll be hundreds of meters away. If they then decide to turn around (since they have to be facing you to shoot you) and come for another run at you...honestly they were probably going to do it anyway.