Most nations spend a notable portion of their defense budget, on disrupting opponents via whisper campaigns, and dividing an opponent from within.

This has been going on through all of recorded history.

Disrupting belief in any important part of your opponent's society, is key. The goal is to cause societal disfunction, an inability to work cooperatively.

Why fight a war, if your opponent destructs from within? Or, almost as good, loses some capacity to make war?

Also good, is if your actions cause your opponent to change regimes, and become aligned with your goals.