Whenever the rich want the poor to die.

There’s no way to win this without committing a lot of troops, and Trump doesn’t like to pull out.
So far, the effect of drone warfare has been to remove all cover and concealment for the infantry, and make armor vulnerable.
At the same time, drones can be launched from almost anywhere, so you can’t prevent drone attacks with air power alone.
You need boots on the ground, and those boots have never been more vulnerable since World War 1.