US President Barack Obama was touched and moved by the "serene" setting of the Ground Zero memorial on Sunday at September 11, 10th anniversary commemorations, a spokesman said.
Obama appeared at the new memorial at the Ground Zero site of the felled World Trade Center in New York, before heading to the crash site of United Airlines Flight 93 in Pennsylvania and then onto the Pentagon.
His spokesman Josh Earnest told reporters aboard Air Force One that Obama believed the monument, consisting of massive fountains sunk into the footprints of the former towers, "meets the moment."
"He was touched by the serene setting of the reading of the names this morning," Earnest said.
"He and the First Lady were particularly moved by the families of those who were lost, who participated in the ceremony, particularly the children."
Obama will deliver remarks at a commemorative event later on Sunday at the John F Kennedy Center for the Performing Arts in Washington, and will honor the "service and sacrifice" of Americans in uniform since the attacks.
He will dwell on the things that have changed in America since 2001, but "the president will also talk about the very important things that haven't changed in the last 10 years," Earnest said.