"This field is now a monument to American defiance", Trump said in remarks near where the aircraft went down 17 years ago. The bell has been rung on every anniversary since 2002, when it was presented to NY by the City of London to honour those who died.
Another plane, United Airlines Flight 93, crashed in a field in Shanksville, Pennsylvania. "They hoped to break our spirit, and they failed".
First Lady Melania Trump, in the background of the photo, is more reserved, perhaps aware that anything other than stoicism on a day like 9/11 might be construed as inappropriate.
Trump, a NY native making his first visit as president to the Shanksville site, will focus on honoring the many lives that were lost that day.
Yet Trump has also received good reviews for other sets of remarks, including his first 9/11 address past year in which he stuck to the topic without ad libbing.
Victims' relatives, survivors, rescuers and dignitaries are gathered on the memorial plaza to remember the deadliest terror attack on American soil.
Smoke pours from the World Trade Center after being hit by two planes September 11, 2001 in New York City.
"No terrorist act can never change who we are", has pointed out, in a tweet, his predecessor, democrat Barack Obama.
And in Washington, Vice President Mike Pence spoke during the memorial observance at the Pentagon, where 125 people were killed when a jet was flown into the building. Thomas Langer said his brother, Timmy, "drank himself to death" after losing his wife, Vanessa, and their unborn child on September 11.
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One email chain was titled "spying", and Democratic files were referred to as "confidential" several times. Despite the tense atmosphere, there were pointed moments of levity.
It will serve as a way to honor those who became sick or died from exposure to toxins released when the Trade Center's twin towers collapsed.
Trump had been in his Trump Tower penthouse, 4 miles (6.5 kilometers) from the World Trade Center, during the 2001 attacks.
Sinodinos says it's better to commemorate the day there than to sit around "being depressed". She calls the progress "amazing".
Over the course of the morning, many public figures posted their solemn commemorations of the terror attacks.
Evan Vucci/APPresident Donald Trump and First Lady Melania Trump arrive at John Murtha Johnstown-Cambria County Airport in Johnstown, Pennsylvania, on Tuesday, Sept. 11, 2018.
Neither rain nor cold kept away 9/11 mourners in Pennsylvania, where a tower of wind chimes was dedicated Sunday to the heroes of United Flight 93.
Almost 3,000 people died after terrorists seized control of four planes, flying two into the World Trade Center in NY and the fourth into the Pentagon.
Since the last anniversary, a truck attack on a nearby bike that killed eight people. "And now it's the tallest", he said at the time.