Yes, Crimea may already be gone. But we have to make absolutely clear – and in the most credible way possible – that Russian military intervention in other regions of Ukraine is a red line that will mean war with Ukrainian and NATO military forces if it is crossed. U.S. and NATO naval forces need to be deployed to the Black Sea in close proximity to the Ukrainian Coast. Military forces of neighboring NATO member countries, meanwhile, should be deployed closer to the Ukrainian border.
This all presupposes that the government in Kiev will request such support, and that Ukrainian military forces, which have been largely absent for the past two days, also need to be ready to be deployed. If Ukraine's military and/or NATO is not prepared to take such measures, then we are simply letting ourselves look foolish with empty threats. But doing nothing would be a terrible misjudgment. Putin has proven agile in asserting Russian interests, and for the West to be effective in its response will require immediate, focused, and forceful action to make Putin recalculate his risk/reward equation.
cnn