Bowe Bergdahl, the only remaining captive American prisoner of war from Iraq and Afghanistan, is alive. The U.S. received a recent "proof of life" video of the U.S. Army sergeant last week at a Middle Eastern embassy, NBC News reported on Wednesday. This is the first video proof of the soldier's condition since February of 2011. 

The video reportedly "shows a frail, shaky Bergdahl." The captured soldier references the early December death of Nelson Mandela, proving that it cannot be very old. According to CNN, the video also references the date of December 14, 2013. A Pentagon spokesperson addressed the U.S.'s failed negotiations for the soldier's release, in response to the news of the recent proof of life: 

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

Bergdahl went missing in 2009, while serving in Afghanistan, reportedly after walking away from his base unarmed. Officials believe he's been held captive by the Taliban-supported Haqqani network in Pakistan. His service and captivity were the subject of a lengthy Michael Hastings investigation in Rolling Stone. Hastings describes how Bowe's health has apparently deteriorated during his time in captivity: 

The videos show a steep decline in Bowe's appearance and mental health. In the first two videos he displays a measured calm, a kind of doped-out serenity that is missing from the most recent installments. Each is typical jihadist propaganda, using Bowe to recite lines criticizing American foreign policy. 

"For his part, Bowe does not appear to be a willing hostage," Hastings wrote. Bergdahl apparently escaped captivity at least once, and was recaptured only with the manpower of five militant fighters. With all the other U.S. military personnel scheduled to come home this year, the new video may spur more action to bring the last one home safe.