President Barack Obama and Vice President Joe Biden place a wreath at the Tomb of the Unknowns at Arlington National Cemetery in Arlington, Va., Sunday, Jan. 20, 2013.  (AP Photo/Susan Walsh)

Photo by: Susan Walsh

President Barack Obama and Vice President Joe Biden place a wreath at the Tomb of the Unknowns at Arlington National Cemetery in Arlington, Va., Sunday, Jan. 20, 2013. (AP Photo/Susan Walsh)