US President Barack Obama speaks while standing behind bullet proof glass during the 10th Anniversary commemoration of the September 11, 2001 attacks at the lower Manhattan site of the World Trade Center September 11, 2011 in New York. Listening behind glass (L) are his wife Michelle Obama (R), Former US President George W. Bush (C) and his wife Laura Bush (L) AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)