Awwal 25, 1432 / April 29, 2011, SPA -- U.S. President Barack Obama on Thursday announced a major change in his national security team. In a statement made in the White House East Room, Obama announced that he was nominating now-Central Intelligence Agency (CIA) Director Leon Panetta to replace Defense Secretary Robert Gates when Gates retires this June. He also announced his nomination of Iraq and Afghanistan war commander General David Petraeus to head the CIA-meaning that he would have to leave the U.S. Armed Forces. Obama will also nominate veteran diplomat Ryan Crocker as U.S. ambassador to Afghanistan. The changes, which require Senate approval, come as the Obama administration confronts numerous national security challenges at home and abroad, including finding a way out of the increasingly unpopular war in Afghanistan and making politically risky cuts to the Pentagon budget.