MILITARY

AP PHOTOS: US marks anniversary of 9/11 attacks

  • From left, President Barack Obama, Defense Secretary Chuck Hagel and Joint Chefs Chairman Gen. Martin Dempsey participate in a ceremony at the Pentagon, Thursday, Sept. 11, 2014, to mark the 13th anniversary of the 9/11 attacks. (AP Photo/Pablo Martinez Monsivais)

    From left, President Barack Obama, Defense Secretary Chuck Hagel and Joint Chefs Chairman Gen. Martin Dempsey participate in a ceremony at the Pentagon, Thursday, Sept. 11, 2014, to mark the 13th anniversary of the 9/11 attacks. (AP Photo/Pablo Martinez Monsivais)  (The Associated Press)

  • From left, President Barack Obama, Defense Secretary Chuck Hagel, and Joint Chiefs Chairman Gen. Martin Dempsey stand at the Pentagon, Thursday, Sept. 11, 2014, during a ceremony to mark the 13th anniversary of the 9/11 attacks. (AP Photo/Charles Dharapak)

    From left, President Barack Obama, Defense Secretary Chuck Hagel, and Joint Chiefs Chairman Gen. Martin Dempsey stand at the Pentagon, Thursday, Sept. 11, 2014, during a ceremony to mark the 13th anniversary of the 9/11 attacks. (AP Photo/Charles Dharapak)  (The Associated Press)

  • A woman walks with a child near United States flags with 1 World Trade Center, rear left, in the background, Thursday, Sept. 11, 2014, in Jersey City, N.J. The country is observing the 13th anniversary of the Sept. 11, 2001 terrorist attacks on the World Trade Center. (AP Photo/Julio Cortez)

    A woman walks with a child near United States flags with 1 World Trade Center, rear left, in the background, Thursday, Sept. 11, 2014, in Jersey City, N.J. The country is observing the 13th anniversary of the Sept. 11, 2001 terrorist attacks on the World Trade Center. (AP Photo/Julio Cortez)  (The Associated Press)

The United States marked the 13th anniversary of the Sept. 11 attacks against a troubling backdrop. The ceremonies came just hours after President Barack Obama told the country he is authorizing stepped-up airstrikes in Iraq and Syria against Islamic State extremists.

In New York City, family and friends of those who died read the names of the nearly 3,000 people killed there, at the Pentagon and near Shanksville, Pennsylvania. In Washington, Obama observed a moment of silence outside the White House with the first lady and Vice President Joe Biden before heading to the Pentagon's 9/11 memorial.

Here's a gallery of photos from Thursday's commemoration.

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