This was the quandary that I faced in December of 1969 when I was charged with the mission of intercepting Viet Cong raiders who were suspected of receiving support from a 'friendly village" in my Area of Operations.
There was one main trail .. well used ,.. which was the most advantageous access to villagers whose daily chore it was to work the fields; every morning, they walked the familiar trail to work their field: out to the fields at dawn, back home at dusk.
Everybody (villagers and Viet Cong) knew we were in the area, and everybody knew that our intention was to intercept VC as they entered the village to receive food, other supplies and intelligence about our counter-VC activities.
And everybody knew the trail that the VC used to enter the village for re-supply; it was the same well-trodden trail that the villagers used to go to their fields to work every damn morning of the year.
I had been putting squad-sized ambushes on that trail for a week, and the members of my squad were on a first-name basis with many of the villagers who walked that trail at dawn on their way to their fields. Finally I decided that the VC were entering the village just before dawn or dusk, quickly taking their daily supplies, and then exiting the area from the same well-trodden trail.
So every night I placed directional Claymore Mines on the trail, and put scouts overlooking the mines to ensure that they didn't harm villagers on their way to work their fields in the morning,
After a few days, I realized that my assumptions were wrong: the VC were not meeting the villagers on the trail; they were using that same trail to boldly enter the village during the dark hours. They knew we couldn't reliably monitor the trail 24/7, and were taking advantage of our "down time" to resupply. And they knew when we set up the Claymores, and avoided those hours. Or else they merged with the villagers, and we could not discern who was a "local" and who was VC, so we didn't attack ANYONE!
Yes, we assumed (and rightly) that the villagers were supporting the VC with food and other supplies .. but not arms or ammunition. I was sure of that. (Maybe not so sure now ... but nobody got hurt!)
My counter decision was to mine the trail during the dark .. after the villagers had returned to their homes and before they had legitimately entered their fields in the early morning. My hope was to rely on the villagers to NOT use the trail at night, but for the VC to use the trail to actually enter the village for resupply.
We were not able to position ourselves to watch the trail at night ( it proved impossible to discern movement at night at that time of the year, and the villagers watched our every movement) so I elected to mine the trail with trip-wires attached to Claymore Mines.
It may have been "A Good Idea", except that the mines would destroy ANYONE who walked that trail .. including the villagers who rose at dawn to go to the fields!
Fortunately, it was my habit to take "Last Watch" on every ambush position, and when I saw villagers entering the trail at Dawn I rousted all of my patrol and directed them to help me disarm the mines.
I had to go "approximately" on the trail (remember, this was semi-dark) where I had set the booby trap ... find the battery which powered the mine(s), and follow the wires to the initiation device. I disconnected it, and then was safe to remove the trip-wires and the Claymore mine and the battery (and attached wires).
I was accustomed to setting-up battery-powered Claymore mines on a nightly basis. I examined each individual mine for any booby traps which might have been added by VC (they did that sometimes) and found no problems in de-activating the directional mine. Then I recovered the wires to the battery and disconnected the battery. (The VC sometimes booby-trapped our mines, rather than avoiding or removing them; they wanted to kill the Americans who had set the command-detonated mines, so we always examined each Claymore for "enhancements".)
The VietNamese villagers have a .. refined sense of humor; they enjoyed changing their work hour to impose the greatest variation of the time when we needed to be aware of friendly activity; they would rise early, or leave late, so that I was required to rise at the most inconvenient time to remove or de-activate the mines I had placed on their common route of travel to the fields.
It became something of a game, when and by which path they would exit their village to enter their fields. I don't think they were trying to aid the VC in this; they were just playing with the "Amers" and they enjoyed the game. They knew who was VC and who was not; and I guess they knew that nothing they could do would cause me to endanger them.
At least, that is what I have always hoped.
By the time I DEROSed Viet Nam, I gained a great deal of respect for the folks who spent their lives in a war zone, and the way they dealty with it. Both US troops and VC/NVA were trying to "Win the Hearts and Minds of the Viet Namese People. I hope that by allowing them to play their silly games, I was able to convince them that we Americans were not only trying to protect them, but to assure them that we also had a sense of humor.
Either that, or they decided that we were incompetent buffoons.
That was okay, too. I always felt that way in Viet Nam.