Barack Obama, Ash Carter, Joseph Dunford stand at attention as the national anthem is played during a memorial ceremony at the Pentagon in Washington to commemorate the 15th anniversary of the 9/11 terrorist attacks.
A young girl holds her mother during a commemoration ceremony for the victims of the September 11 terrorist attacks at the National September 11 Memorial and Museum fifteen years after the day.
A man becomes emotional during a moment of silence during a ceremony for the 15th anniversary of the attacks on the World Trade Center at the National September 11 Memorial, in New York, Sunday, September 11, 2016.
An FDNY firefighter stands as part of an honor guard at the FDNY Memorial Wall near the World Trade Center on Sunday, September 11, 2016, on the 15th anniversary of the attacks on the World Trade Center in New York.
People hold photos of their loved ones during a ceremony for the 15th anniversary of the attacks on the World Trade Center at the National September 11 Memorial, in New York, Sunday, September 11, 2016.