Choose any national conflict going on somewhere in the world right now. By definition of “conflict”, there must be at least two sides.
For a particular “friendly” side, choose a border encompassing where the “enemy” side is located.
Overnight, every human mysteriously disappears within that border. There is no physical remnants of those people, but everything else remains (cars, houses, plants, animals, etc.). If it contained human DNA, it’s gone. Men, women and children are gone. Combatants from both sides are equally vanished if they were located within the border during the event.
There is no proof that the friendlies did this or that they even have this capability. Any cameras pointed at people during the event record only static.
How would the world react to such an event? Who would claim the empty territory?
I suppose enemy ex-pats may want to reclaim their homeland. At first, most settlers would be reluctant to move to a place where so many have “died”. But over time, people would get over that phobia when the event never repeats again.
If someone inherit property from the affected area, are they really in any position to defend it?
Would the world allow the friendly side to move settlers in and claim the territory? Or would it become a permanent no man’s land?
Some concrete examples: If the Israelis wake up one morning and found all the Palestinians were gone, would that conflict end?
If the United States discovered that Iraq, Iran, Afghanistan, Pakistan, Yemen, Libya and North Korea were suddenly empty, I suppose the first thing that happens is the President orders Seal Team Six into Pakistan and North Korea to secure the nukes. But what happens after? Do we send more troops or just cut our military budget accordingly?