Not necessarily. Generally, a conventional war ends when one side surrenders, usually because it knows it can't win and wants to minimize further losses. If we reach a point where unmanned weapons are the ultimate tool for destruction, then it makes sense that by the time the AI combatants reach a point where they could target enemy populations, the war would already be decided, and the nation about to have its people killed would surrender. There will be exceptions, but it would be no worse than current war, and at least potentially be better.
That is of course assuming that the most efficient strategy to achieve a surrender doesn't actually end up being a bypass of enemy AI and direct targeting of human populations. This would only be possible if there's a huge mismatch between offensive and defensive capability. But then you end up with a MAD situation similar to what we have with nukes.
That said, I expect that the flip-side is that this tech would ultimately make a guerilla war by a local population against an occupying force very very ugly for the guerillas.