President Donald Trump spoke at the 9/11 memorial service in Shanksville, Pennsylvania, on Tuesday, recalling the attacks of September 11, 2001.

Trump praised the valor of the 40 passengers and crew members of Flight 93 for resisting the terrorists in control of the hijacked plane, which led to the crash in a Pennsylvania field.

“At this memorial, on this sacred earth, in the field beyond this wall, and in the skies above our heads, we remember the moment when America fought back,” Trump said, praising the Americans aboard the flight who “changed the course of history” by resisting the terrorists.

Trump recognized the heroes who planned and voted to take action against the terrorist hijackers.

“At that moment, they took their fate — and America’s fate — back into their own hands,” he said.

Trump recognized the nearly 7,000 service members who died since 9/11 facing “radical Islamic terrorism” and promised he would do everything he could to prevent another attack on American soil.

“This field is now a monument to American defiance,” he said. “This memorial is now a message to the world: America will never, ever submit to tyranny.”

Trump acknowledged the completion of the Tower of Voices, a new monument at the Flight 93 memorial site featuring wind chimes for each of the 40 Americans who died on the flight.

“Every time we hear those chimes playing in the wind, we will remember The Forty,” he said.

The president shared stories of Americans aboard the flight who contacted their loved ones before their struggle with the hijackers.

“We will remember their faces, their voices, their stories, their courage, and their love,” he said. “And we will remember that free people are never at the mercy of evil because our destiny is always in our hands.