President Obama spoke Friday afternoon as the body of slain Libya ambassador Christopher Stevens was returned to the United States.
Obama and Secretary of State Hillary Rodham Clinton both spoke this afternoon as a "transfer of remains" ceremony at Andrews Air Force Base.
The ceremony was scheduled for 2:15 p.m.
Stevens and three other Americans died Tuesday after protesters stormed the consulate in Benghazi, Libya, on Tuesday.
Some protesters cited an online anti-Islam film as their reason; but U.S. officials are also investigating the possibility of a pre-planned attack designed to coincide with the 9/11 anniversary.
Obama -- who has vowed to capture the perpetrators -- praised Stevens in remarks on Tuesday:
"It's especially tragic that Chris Stevens died in Benghazi because it is a city that he helped to save.
At the height of the Libyan revolution, Chris led our diplomatic post in Benghazi. With characteristic skill, courage, and resolve, he built partnerships with Libyan revolutionaries, and helped them as they planned to build a new Libya.
When the Qaddafi regime came to an end, Chris was there to serve as our ambassador to the new Libya, and he worked tirelessly to support this young democracy, and I think both Secretary Clinton and I relied deeply on his knowledge of the situation on the ground there.
He was a role model to all who worked with him and to the young diplomats who aspire to walk in his footsteps."