President Donald Trump delivered remarks at the Pentagon commemorating the 24th anniversary of the Sept. 11 attacks on the United States.

"On that fateful day, savage monsters attacked the very symbols of our civilization. Yet here in Virginia and in New York and in the skies over Pennsylvania, Americans did not hesitate," Trump said. "They stood on their feet, and they showed the world that we will never yield. We will never bend. We will never give up. And our great American flag will never, ever fail."

Trump told personal stories of heroes and victims of the attacks, saying "that day we learned that the American heroic spirit was all around us."

The president also issued a warning that anyone who would attack the U.S.

"In the years to follow, America's warriors avenge the fallen and send an unmistakable message to every enemy around the world," Trump said. "If you attack the United States of America, we will hunt you down and we will find you. Go all over this sometimes magnificent earth. We will crush you without mercy. And we will triumph without question. That's why we named the former Department of Defense the Department of War."

President Donald Trump and first lady Melania Trump have arrived at the Pentagon to observe the 24th anniversary of the terror attacks of Sept. 11, 2001. Both are wearing black, with the first lady donning sunglasses and Trump wearing a red tie.

They are accompanied by Pentagon chief Pete Hegseth and Chairman of the Joint Chiefs of Staff Gen. Dan Caine.

President Donald Trump is scheduled to begin his Thursday at the Pentagon, where he and first lady Melania Trump will attend a ceremony marking the 24th anniversary of the terror attacks of Sept. 11, 2001.

Trump is expected to arrive for the ceremony at about 8:45 a.m. ET, according to the White House.

The Pentagon began the day of remembrance with a flag unfurling at dawn, an event attended by Secretary of Defense Pete Hegseth.

-ABC News' Isabella Murray

The Department of Labor Office of Inspector General (DOL-OIG) has opened a review about the "challenges" that the Bureau of Labor Statistics "encounters collecting and reporting economic data," a DOL-OIG spokesperson told ABC News on Wednesday.

In a letter sent to the BLS acting commissioner, the DOL-OIG's office said that they are initiating the review as the bureau announced that they would reduce data collection for two key inflation measures: the Consumer Price Index (CPI) and the Producer Price Index (PPI). The review will focus on the challenges of collecting that data.

The review will also look into the challenges and mitigation strategies for the bureau as it collects and reports monthly employment data in the wake of yesterday's benchmark jobs revision, according to the letter.

-ABC News' Michelle Stoddart

In the wake of the shooting of political activist Charlie Kirk, the White House made the decision to move the 9/11 Commemoration Ceremony at the Pentagon into the courtyard -- away from the 9/11 memorial where the somber ceremony has been held for decades.

"After yesterday's heartbreaking political assassination of Charlie Kirk, a decision was made to move the ceremony to the courtyard," a White House official said.

When pressed about who made the decision, the official confirmed that the White House made the call to move it into the courtyard.

U.S. Secret Service deferred to the White House when asked for comment.

-ABC News' Michelle Stoddart