Russia plans S-300 tests UPI 2/18/2013 2:18:28 PM MOSCOW, Feb. 18 (UPI) -- The Russian military said Monday it was planning military drills in the west of the country to test its S-300 surface-to-air missiles. The Russian military said Monday it was planning tests for the S-300 to engage Russian Su-27s and MiG-31s posing as enemy aircraft, reports state-run news agency RIA Novosti. The S-300 is considered one of the more potent missile defense systems in the Russian arsenal. It reportedly can track up to 100 targets at once and engage up to 12. Acting U.S. Undersecretary for Arms Control and International Security Rose Gottemoeller left Russia last week after discussing defense issues. Moscow has expressed concern about Washington's missile defense plans for Eastern Europe. "While in Moscow, she engaged in a frank and productive dialogue with Deputy Foreign Minister Sergei Ryabkov and other Russian counterparts on a range of arms control, nonproliferation and international security issues," a statement from the U.S. State Department read. Russia says U.S. missile plans for Eastern Europe would upset the regional balance of power. Washington said defensive measures are needed to protect against Iran and North Korea.