U.S. President Barack Obama (C), lays a wreath while flanked by his wife first lady Michelle Obama (L) Secretary of Defense Leon Panetta (2nd-L), and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey (R) during a 9/11 remembrance ceremony at the Pentagon, September 11, 2012 in Arlington, Virginia. U.S. President Barack Obama joined staff and family members at the Pentagon to commemorate the eleventh anniversary of the September 11 attacks.