In a White House statement, Obama also said he had ordered "all necessary resources to support the security of our personnel in Libya, and to increase security at our diplomatic posts around the globe."
The attacks occurred Tuesday night in the eastern city of Benghazi by protesters angry over a film that ridiculed Islam's Prophet Muhammad, according to Libya officials. Ambassador Chris Stevens was killed when he and a group of embassy employees went to the consulate to try to evacuate staff as the building came under attack by a mob guns and rocket propelled grenades. Three other Americans were also killed.
Obama called Stevens a "courageous and exemplary representative of the United States."
"I strongly condemn the outrageous attack on our diplomatic facility in Benghazi," Obama said in the statement. The four Americans, he said, "exemplified America's commitment to freedom, justice, and partnership with nations and people around the globe."
Stevens was a career diplomat who spoke Arabic and French and had already served two tours in Libya, including running the office in Benghazi during the revolt against Libyan leader Moammar Gadhafi. He was confirmed as ambassador to Libya by the Senate earlier this year.
His State Department biography, posted on the website of the U.S. Embassy to Libya, says he "considers himself fortunate to participate in this incredible period of change and hope for Libya."
Stevens joined the Foreign Service in 1991 and spent his early State Department career at posts in Saudi Arabia, Egypt, Syria and Israel. After working for the Senate Foreign Relations Committee staff for Sen. Richard Lugar, R-Ind., Stevens was posted to Libya as deputy chief of mission.
In that post, Stevens wrote several confidential cables back to Washington, describing Gadhafi's bizarre behavior. During the 2011 revolt against Gadhafi, he was one of the last American diplomats to stay in Tripoli and after the embassy was closed, he was appointed to head the U.S. liaison office to the Transitional National Council.
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