Defense Secretary Chuck Hagel and Army Gen. Martin E. Dempsey, chairman of the Joint Chiefs of Staff, greet President Barack Obama as they gather to mark Memorial Day at Arlington National Cemetery in Arlington, Va., May 26, 2014. Obama participated in a wreath-laying ceremony at the Tomb of the Unknowns to honor the fallen before he, Hagel and Dempsey spoke to about 3,000 people in the cemetery's Memorial Amphitheater.