EE.UU. conmemora el 10º aniversario del 11-S
U.S. President Barack Obama and first lady Michelle Obama meet families of 9/11 victims at the Pentagon Memorial on the 10th anniversary of the attack on the Pentagon in Washington September 11, 2011. REUTERS/Kevin Lamarque (UNITED STATES - Tags: DISASTER ANNIVERSARY)
U.S. President Barack Obama (L) and first lady, Michelle Obama (R) walk along the memorial site for the victims of Flight 93 during ceremonies marking the 10th anniversary of the 9/11 attack in Shanksville, Pennsylvania, September 11, 2011. REUTERS/Jason Cohn (UNITED STATES - Tags: ANNIVERSARY DISASTER)
ARLINGTON, VA - SEPTEMBER 11: Service members carry flowers to each marker in the Pentagon Memorial during a memorial service at the Pentagon September 11, 2011 in Arlington, Virginia. Vice President Joseph R. Biden, Secretary of Defense Leon E. Panetta, Chairman of the Joint Chiefs of Staff Navy Admiral Mike Mullen and others will attend the service at the Pentagon Memorial to commemorate the 10th anniversary the September 11, 2001 terrorist attacks on the United States. Brendan Smialowski/Getty Images/AFP