Well, Russia is sort of holding back. They have tactical nukes, not sure how many of those nato has without the US. And going ballistic doesn’t end well for anyone. But Russia need the land of major nato members. They will pick on non-nato countries mostly, and more often they will do it by cutting off trade routes and such. Maybe they use thier now seasoned military to pick off some minor nato members, just to distract Nato from everything else. With the US pulling back from the international stage, Russia and Chine can divvy up a lot of the world.