The alliance is capable of dealing with the bully, but it clearly prefers not to, and will probably say meh even if Ukraine gets totally destroyed. Which may cause some leaders in Ukraine, just as some already do in EU/America, think that maybe the whole nation building and bear poking on its doorstep wasn't worth it. But it is also possible that Russia won't be strong enough to keep this up and some stalemate will be reached. Time will tell.