The situation in Ukraine is extreme. Just days after President Obama announced additional economic sanctions on Russia, a Malaysia Airlines plane carrying nearly 300 people was apparently shot out of the sky. Disputes over who is responsible will likely continue, even after the results of an investigation are finalized. Assuming Russia is in some way responsible — either directly or by supporting separatists — what more can the U.S. and Europe do to rein in Russia? Are we in for another Cold War, or is it time to take more targeted action? Send no more than 150 words with your name, address and phone number to firstname.lastname@example.org. Deadline is Wednesday.