Tension between the United States and Russia is once again on the rise. In the wake of a limited U.S. strike on Syria , in which two U.S. Navy destroyers fired 59 Tomahawk cruise missiles at the Shayrat air base in western Homs on April 6, the Kremlin pulled a 2015 agreement with Washington designed to avoid military collisions in Syrian airspace. The attack will raise the stakes of U.S. Secretary of State Rex Tillerson's approaching visit to Moscow on April 11-12. Since 2013, Russia has been trying to use the Syrian civil war as leverage in its negotiations with the United States on other issues, but so far its strategy hasn't yielded many results. Though Washington notified Moscow prior to the attack in order to avoid drawing the Russians into the clash, the Kremlin will use the heightened risk of U.S.