President Barack Obama will take part in two somber ceremonies Thursday marking the 13th anniversary of the September 11th terrorist attacks on the United States.
Obama, accompanied by first lady Michelle Obama and Vice President Joe Biden, will lead a moment of silence on the South Lawn of the White House at the moment the first hijacked passenger jet crashed into one of the twin towers of New York City's World Trade Center.
President and Mrs. Obama will later attend a ceremony at the Pentagon, the U.S. military headquarters, where hundreds were killed after a third hijacked jetliner crashed into the complex.
Thursday's observances come hours after Obama announced an enhanced strategy of fighting Islamic State militants operating in Iraq and Syria.
In New York, survivors of the nearly 3,000 people who died when the World Trade Center's twin towers collapsed will carry out the annual ritual of reading their loved ones' names aloud. This year's ceremony is the first since the opening of the September 11 Museum, which holds artifacts and photos connected to the attacks. The World Trade Center complex itself is nearly rebuilt, with the main skyscraper due to officially open later this year.
Another observance will be held in the town of Shanksville, Pennsylvania, where a fourth airliner hijacked that day crashed before reaching its likely target of Washington, D.C. During the ceremony, the Congressional Gold Medal, the nation's highest civilian award, will be presented for the first time in honor of the passengers and crew of United Airlines Flight 93.
The commission that investigated the September 11 attacks concluded Flight 93 crashed as passengers fought with the hijackers to regain control of the plane, killing everyone on board. The crash site has been turned into a national memorial in honor of the plane's passengers and crew.