A NYPD officer pauses at the edge of the south reflecting pool at the National 9/11 Memorial and Museum during ceremonies marking the 16th anniversary of the attacks in New York

A NYPD officer pauses at the edge of the south reflecting pool at the National 9/11 Memorial and Museum during ceremonies marking the 16th anniversary of the attacks in New York

A New York City Police Department (NYPD) officer pauses at the edge of the south reflecting pool at the National 9/11 Memorial and Museum during ceremonies marking the 16th anniversary of the attacks in New York, U.S., September 11, 2017. REUTERS/Brendan McDermid