To this day, I remember a scene from the film released in the year
2000 depicting a court-marshal of a military officer played by Samuel
L. Jackson.
  To give background on one of the characters, a flashback is shown
that depicts an American officer (forgot which character) using an
unusual tactic to stop a North Vietnamese attack - he basically finds
the NVA officer leading the assault, points a gun to the man's head
and tells him to order his men to withdraw.  He does so, ending the
engagement.
  My question is: I thought this was a very unconventional thing to do
on a battlefield.  Is this something "permitted" by US military law
for an officer to do?  It just seemed so... un officer-like, because
it was more about ending a threat than destroying an enemy, which is
what our soldiers are supposed to do.
  Please don't interpret this as "hey let's throw our guys in harm's
way just to achieve an objective" which I don't believe in, but as
"technically, was this officer doing the right thing?  And if not,
what are the possible consequences to that officer?"

I am not a military officer but did spend some time working with the
Army and Navy at several overseas locations. As such, I was required
to familiarize myself with military law as it applied to civilians.
Sometimes I kept reading.

During battle, about the only time a soldier is restricted from
shooting an enemy soldier is when the enemy is surrendering. There are
other situations, but they don't apply here.

The tactic used by Jackson's character, Col. Terry L. Childers, is
ridiculous. In a situation such as this the soldier would order the
opposing commander to surrender his troops, not withdraw.

Now as to legality of the tactic-- what if the gun being used was not
loaded-- Would that make a difference? What if Jackson's character
instead merely threatened to kill the NVA rather than the grandiose
gun-to-the-head bit?

Considering Vietnam was an undeclared war, used exaggerated and
falsified intelligence to get the US to engage, had no well-defined or
articulated strategy, and involved the installation of puppet leaders,
the depicted action can hardly be said to be anything approaching the
atrocities committed.

Golly, that reads like this week's news...

Maybe it is good that members of the Judge Advocate's Corps don't see
much front action  - or maybe they should ...