President Trump said Monday that terrorists have “no place to hide” as he marked the 16th anniversary of the Sept. 11 terrorist attacks in New York, Washington and Pennsylvania.

“There is no dark corner beyond our reach,” and the United States will be relentless in confronting terrorism, Trump said during remarks at the Pentagon.

“Our eyes were opened to the evil we face,” from international terrorism, Trump said.

Joint Chiefs of Staff Chairman Gen. Joseph F. Dunford Jr. and Defense Secretary Jim Mattis stood beside Trump as he spoke to a crowd that included families of some of the 184 Pentagon employees and airline passengers who died in the attack there.

“Mr. President, your military does not scare,” Mattis told Trump.

Earlier, Trump led a moment of silence in a brief, somber ceremony at the White House. Trump and first lady Melania Trump walked onto the South Lawn and stood as bells tolled for the first 9/11 anniversary of Trump’s presidency. They then bowed their heads and stood silently before placing their hands on their hearts as a bugler played taps.

Vice President Pence traveled to Shanksville, Pa., where one of the four hijacked jetliners crashed after passengers overpowered the hijackers. Two planes hit and destroyed the World Trade Center in New York and the other crashed into the Pentagon.

Nearly 3,000 people were killed in the coordinated attacks directed by al-Qaeda leader Osama bin Laden.

Trump, a frequent early-morning tweeter, did not post any messages ahead of the 8:46 a.m. ceremony at the White House.

Pence is scheduled to speak later Monday morning at the rural site of the Pennsylvania crash. He and his wife will tour the Flight 93 National Memorial nearby.