For almost all of history, “war” meant battles of attrition. You fought wars by killing as many of the other guys as possible. If you killed enough, their side would be scared into submission. Every single war up to WW2 was fought this way.
Then we got nuclear weapons, and people luckily realized that fighting a war of attrition with nuclear weapons is too high of a price to pay.
Wars fought since WW2—Korea, Vietnam, both Iraq Wars—have many vestiges of wars of attrition. But they are fundamentally lopsided. Any army facing a Western force is quickly overpowered and dissolves into a guerilla force blended in with the civilians. Modern wars are not fought against governmental structures or institutions, they are fought against ideology—Communism, or Islamic Extremism, or Drugs, or Terror, or Crime.
This state of affairs makes no sense. You cannot fight a war against an ideology. And you cannot spread an ideology like democracy by dropping bombs on civilians and killing tens of thousands of them.
Fundamentally, wars in the nuclear age resemble broad-scale police actions. You have an overwhelming force (American or NATO military) vs. lawless guerillas operating in civilian areas. We should not fight them using the tactics and weapons of wars of attrition. We should fight them like police fight criminals. Military technology should evolve so that it is far less lethal, far better at protecting civilians in areas where it is deployed. Airstrikes and drone attacks that sacrifice the lives of 30 civilians to kill one terrorist are absolutely immoral and strategically counterproductive. We can capture and kill terrorists without declaring “war” on them, by treating them like the criminals they are, and by sparing the civilians they shield themselves with.
Once we try to do this in earnest, there’s no reason to have war. Only police action would remain, and the world will be better off.