Story highlights First video of Bergdahl in nearly three years surfaces

Army soldier was taken captive in 2009, believed held by Taliban-aligned group

U.S. efforts to free Bergdahl, including negotiating for his release, have so far failed

Family asks in statement that captors release Bergdahl

The U.S. military has obtained new video apparently made by those holding the lone American prisoner of war, Army Sgt. Bowe Bergdahl

A U.S. military official told CNN the clip shows the Wood River Valley, Idaho, native in diminished health from the effects of close to five years in captivity.

He was seized in Afghanistan in June 2009 and is believed held by the Taliban-aligned Haqqani network in Pakistan, the official said.

The so-called proof-of-life video, the first of him in nearly three years, has a reference to December 14, 2013.

CNN has not seen the video.

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U.S. efforts to free Bergdahl, including negotiating for his release, have so far failed.

"Sgt. Bowe Bergdahl has been gone far too long, and we continue to call for and work toward his safe and immediate release," a Pentagon spokesman said.

"We cannot discuss all the details of our efforts, but there should be no doubt that on a daily basis -- using our military, intelligence and diplomatic tools -- we work to see Sgt. Bergdahl returned home safely," the spokesman said.

His family, who received a letter from him last year via the Red Cross, issued a statement in response to the latest video.

"As we have done so many times over the past 4 and a half years, we request his captors to release him safely so that our only son can be reunited with his mother and father," the statement reads. "BOWE - If see this, continue to remain strong through patience. Your endurance will carry you to the finish line. Breathe!"

Bergdahl was 23 when he was captured after finishing a guard shift at a combat outpost in southeastern Paktika province.

The U.S. government acknowledged in May 2012 that it was engaged in talks with the Taliban to free Bergdahl.

The discussions moved in fits and starts because of U.S. concerns that any Taliban prisoners swapped for Bergdahl might be repatriated and allowed to rejoin the fight.

Later that year, however, the White House announced it was willing to send five Taliban prisoners to Qatar in exchange for Bergdahl.