We had exactly this attitude during the cold war lol. Nato's actions here are absolutely consistent with the principles of deterrence worked out during the cold war.

There's a reason there were endless proxy wars, guerrilla trainings, and secret arms supplying back then. Neither side would risk a direct conflict with the other, so they did all that instead.

You'll notice that's the exact same toolbox they're drawing on now. They didn't invent this shit for putin.