US President Barack Obama touches the names of victims engraved on the side of the north pool of the World Trade Center site as former President George W Bush, first lady Michelle Obama and former first lady Laura Bush (obscured) look on during ceremonies marking the 10th anniversary of the 9/11 attacks on the World Trade Center, in New York Sept 11, 2011. [Photo/Agencies]

A list of names of victims of the 9/11 attacks are pictured prior to ceremonies at the site of the World Trade Center in New York, Sept 11, 2011. [Photo/Agencies]