Defense Secretary Robert Gates said the military continues to "spare no effort" in locating missing soldiers and prisoners of war.

"I've spent nearly four years as secretary of defense, every day of it at war and a time of great challenge," said Gates at the ceremony held on the grassy grounds outside the Pentagon.

"My visits with troops from those still in basic training to those still on the front lines in Afghanistan give me a focus that guides me every day. I must do and will do everything I can to make sure that they have what they need to accomplish their mission and come home safely."

There is currently one soldier in Iraq listed as captured and one in Afghanistan: Staff Sgt Ahmed Altaie was captured in 2006 and Spc Bowe Bergdahl, in 2009.

On the third Friday of every September, ceremonies are held across the country to commemorate the 83,923 America soldiers, from WWII to present, who the Defense POW Missing Personnel Office lists as unaccounted for.

The White House issued a Presidential Proclamation this week ordering that the black and white POW/MIA flag be flown over the White House and U.S. Capitol today, as well as over post offices and various government buildings across the country.

"Since we gathered here for last year's POW/MIA recognition day, teams from the Department of the Defense have accounted for 66 formerly missing Americans," said the defense secretary. "Fifteen of those found and returned to their families fought in the Vietnam War, 16 fought in the Korean War, 34 fought in the Second World War and one man fought in the First World War. This is slow and painstaking work. We pursue it doggedly."

General James Cartwright, USMC, Vice Chairman of the Joint Chiefs of Staff, was also in attendance. He and Gates encouraged attendees to visit a new POW/MIA exhibit at the Pentagon, which features stories of soldiers who were imprisoned. Gates said the stories speak to such universal truths that "one even dares to hope that those far from the battlefield, those at home who still suffered and still feel the painful loss, may find solace in hearing them."

Recounting the story of Vice Admiral James Stockdale, who served eight years as a prisoner of war, Gates described how Stockdale was in a state of his lowest physical and emotional ebb at the Hanoi Hilton when a comrade slipped him a roughly scrawled note with words from a poem: "It matters not how strait the gate, how charged with punishments the scroll, I am the master of my fate; I am the captain of my soul."

After the speech, attendees looked up at the cloudless sky, where a joint service aerial team, consisting of two Air Force F-15E's, one Navy F/A-18, one Marine F/A-18 and four Army UH-60's flew above as part of the ceremony.