ARLINGTON, VA - SEPTEMBER 17: Secretary of Defense Robert M. Gates (L) and Vice Chairman, Joint Chiefs of Staff, Gen. James E. Cartwright (R) answer questions during a press briefing at the Pentagon on September 17, 2009 in Arlington, Virginia. Gates spoke primarily about a change in strategy on missile defense planning that would scrap a plan proposed by former U.S. President George W. Bush and instead focus efforts on revising the system to counter possible threats posed by shorter range Iranian missiles.