I believe this was a wounded teen who was fleeing into the woods. The story goes that they chased him down and shot him. Not exactly like he was not surrendering.
fso301 is right. A dead VC - what's the big deal?
Compare it to the Highway of Death in Gulf War I. The enemy was engaging in a tactical retreat, not a surrender.
The VC fleeing into the woods may have been running towards cover and his stash of grenades or his AK-47, and upon reaching it would have turned around and opened fire on the American troops.
War is not, and should not be, fought under Marquis of Queensbury rules. Sometimes you have to shoot a fleeing enemy in the back.
Is this the unarmed civilian incident Admiral Zumwalt complained about? He said Kerry was was a pain in the butt, loose cannon, running around shooting people in the back.
If he was fleeing, he was doing so with a presumably hostile intent otherwise, he would have surrendered. Nothing wrong in such situation with shooting him in the back.
Even if he surrendered but changed his mind and made a run for it, there's still absolutely nothing wrong with shooting him in the back.
Even if he surrendered and made some sudden "wrong" move, there would still be nothing wrong with shooting him.
I heard from the lips of one of the Vietnam Vets against Kerry (on Sean Hannity's talk show) that the kid had been shot up by machine gun fire, and was in pretty bad shape. Kerry may have done a compassionite thing by ending it for him - don't know the details, but can allow the thought.