Nuke 'em from orbit
It is prohibited to kill or wound an enemy who is surrendering or who is hors de combat.
...is the rule from the geneva convention.
I think this Marine was justified in doing whatever
he did. If he had not shot this insurgent, and the
insurgent activated his suicide belt or a hand grenade
killing everyone including the reporter, there would be
stories complaining about how the marines don't protect
imbeds. If the guy hasn't actively surrendered, he's a
combatant until he's dead or obviously hors de combat.
In the age of chivalry, hors de combat meant that you couldn't
handle a sword or mount your horse. In an age where all you
need to do is press a button to set off an explosive charge, when
are you out of the fight?
If I were president Bush I'd give him a presidential pardon. Of course,
if I were president, Fallujah would be a molten glass filled crater, so maybe
I'm not the best person to ask.