President Donald Trump is set to join Homeland Security Secretary Markwayne Mullin at the Pentagon at 9:30 a.m. for a memorial to commemorate the 25th anniversary of the Sept. 11 terrorist attacks.
The president was initially slated to attend a ceremony in New York, but then shifted plans to deliver an address at the U.S. Military headquarters in Arlington, Virginia.
What to know about the memorial ceremonies on 9/11
On Sept. 11, 2001, at 9:37 a.m., American Airlines Flight 77 crashed into the side of the Pentagon after it was hijacked. The aircraft was carrying 64 passengers and crew members, who died upon impact. Another 125 people inside the Pentagon were killed when the plane struck.