He would if he had the backing of North Korea and China. They would have a standing army larger then the rest of the world combined just about. Of course, I think he's just postulating to get the Crimea land from the Ukraine for free.
China wouldn't back Russia. I don't know why people like to equate China and North Korea. China has spent the last 30 or so years trying to build relations with the rest of the world, not to mention they need us more than we need them. If anything China would be neutral. North Korea on the other hand. Who knows.