The Monroe Doctrine states that the United States of America is in charge of policing the Western Hemisphere, but that the UN is in charge of policing the Eastern Hemisphere.
This means that the UN can take care of Russia, and the United States of America should only step in IF ASKED BY THE UN.
Obama, keep us out of WWIII. Leave Russia and the Ukraine to the UN, and quit wasting our time, money, energy, and effort on waging wars where we don't belong.