Direct action action on one military superpower from another doesn't happen anymore, not since the proliferation of nuclear weapons. Any such action would have

Direct action action on one military superpower from another doesn't happen anymore, not since the proliferation of nuclear weapons. Any such action would have unthinkable consequences for humanity. America's weapon of choice is economic devastation via sanctions, it can leverage its position in the world to convince its allies to follow suit for added effect. Russia, on the outside of NATO, is forced to play a more subtle game, sowing discord and long term instability.