Actually no they don't usually, thank god. You are telling on yourself at the core of the essay here. You are arguing 1) Might is right, seriously a terrible argument, shameful. And 2) you are arguing for a very aggressive form of imperialism, also terrible.

If you argue Russia can justifiably invade its neighbors because America could hypothetically justifiably invade its neighbor, and most countries could, would, and have done the same and that justifies Russian violence, then where is the space for peace? This means endless war and you justified all of it. Any country at anytime can claim they feel threatened or that they have claims over their neighbor just like Russia did.

The alternative is to at least attempt to uphold international borders especially if they have been agreed upon. And to refrain from interfering in internal matters of other countries especially militarily. The exception to military action would be when a country is invaded by an aggressor and then the rest of the world should help that country expel the invader. We've done a terrible job on these principles especially when one of the permanent members of the UNSC is involved but at least we can have a little hope however small. Your prescription of reverting to a version of the violent might is right imperialism of the past is a very dark vision for the future.