But this year, both the Trump White House and the Trump presidential campaign seemingly made a point of including the phrase.
On Tuesday, Michael Glassner, the Trump campaign's chief operating officer, said in a statement, "This day reminds us of the need for America's vigilance against radical Islamic terrorism and its ongoing threat to our freedoms, as President Trump has done so honorably as our Commander-in-Chief."
The flight was hijacked by four al-Qaeda members, who may have been planning to fly it into the U.S. Capitol. As passengers and crew sought to regain control of the plane, it crashed into a field outside of Shanksville. All 44 people aboard were killed.
A White House statement Monday marking Patriot Day used the phrase "radical Islamic terrorists," and not al-Qaeda to refer to the hijackers.
By the time Trump took the stage in Shanksville, however, he already had appeared to undermine the solemnity of the day. Trump began Tuesday morning by raging against his Justice Department in a series of tweets. Later, on the way to Pennsylvania, the president gave photographers a thumbs up outside Air Force One, and upon landing, he pumped both fists at his cadre of greeters.
Trump has a complicated history with the 9/11 attacks. On the day of the actual attacks, he was asked by a local TV station about a building he owned at 40 Wall Street. Instead of reflecting upon the loss of life just hours earlier, Trump falsely claimed that with the World Trade Center having collapsed, his own building was now "the tallest" in the city.
In fact, a nearby building on Pine Street was 25 feet taller. Trump described how, according to his staff near the World Trade Center, "Wall Street is littered with two feet of stone and brick and mortar and steel."
Trump has also used the 9/11 attacks to stoke unfounded fear of Muslims. During Trump's 2016 presidential campaign, he also falsely claimed to have seen video of Muslims in New Jersey celebrating the collapse of the towers.
"There were people that were cheering on the other side of New Jersey, where you have large Arab populations," Trump said on ABC's "This Week" in late 2015. "They were cheering as the World Trade Center came down. I know it might be not politically correct for you to talk about it, but there were people cheering as that building came down — as those buildings came down," Trump said.