Army Sgt. Bowe Bergdahl has provided a "gold mine" of useful intelligence about the militants who held him captive for years in Pakistan, and his experience has injected valuable lessons into the military's program that instructs troops in how to avoid and escape capture, experts testified during Bergdahl's sentencing Tuesday.

Those experts said Bergdahl’s decision to abandon his post in Afghanistan in 2009 produced an unintended consequence: His detailed recollections of his captors’ tactics, methods of detainment and other information were so valuable that intelligence agencies and military doctrine were dramatically improved, potentially adding a new foil to the factors being weighed by a military judge to determine Bergdahl’s punishment, if any.

Terrence Russell of the Joint Personnel Recovery Agency, the lead Pentagon group for recovering prisoners of war and other captives — which also produces related training and doctrine — testified that Bergdahl’s debriefing contributed to lessons taught to U.S. troops and allied militaries, adding that Bergdahl still has intelligence that has yet to be collected that could help troops in Afghanistan right now.

“Can you give him to me now? I need him now. I needed him three years ago,” Russell said. “The fact I can’t get that information is wrong.” Russell added that he has debriefed more than 120 American captives, more than any other U.S. official.

Intelligence analyst Amber Dach leaves the Fort Bragg courtroom facility after testifying for the defense Tuesday. (Andrew Craft/AP)

The defense appeared to use testimony from Russell and a former Defense Intelligence Agency analyst to suggest that there is a national security interest in showing Bergdahl leniency.

Army Col. Jeffery R. Nance, the presiding judge who will determine Bergdahl’s potential punishment, is expected to announce the soldier’s sentence this week.

Bergdahl pleaded guilty Oct. 16 to desertion and misbehavior before the enemy, which carries a maximum of life in prison.

Amber Dach, the lead intelligence analyst tracking Bergdahl, said initial intelligence collection was difficult in the region. The Taliban-linked Haqqani network, which held Bergdahl in Pakistan, executes “robust disinformation operations” to deceive analysts sifting through large amounts of raw data, she said.

That changed weeks after Bergdahl was recovered and offered a “gold mine” of useful intelligence, including actionable information on militant activity that was immediately sent to commanders in Afghanistan, Dach said.

“It reshaped the way we did intel in the area. It confirmed what we knew and what we did not know,” she said.

Dach did not elaborate on what kind of information he provided, but she did say Bergdahl helped analysts “build a captor network like never before,” suggesting that he offered information such as details on key Haqqani leaders, preferences for terrain, and how guards transport prisoners and pick prisoner holding sites for the group, which uses ransom to fund its operations.

The testimony Tuesday contrasts with a slate of other witnesses called by the prosecution — troops who say they were wounded on the battlefield during search-and-rescue operations launched to find Bergdahl.

The defense has suggested that Bergdahl's treatment should be a mitigating factor in determining his sentence. Russell said the brutality and duration of Bergdahl's captivity, which included torture and confinement in a cage, amounted to the worst case of prisoner treatment involving a U.S. service member since the Vietnam War.

Nance also will weigh other positive contributions Bergdahl has made since his rescue.

Doctrine and strategies to recover missing personnel are honed to specific regions, but no U.S. soldier other than Bergdahl had ever been captured in Afghanistan, making him a uniquely valuable source of information as the Trump administration increases troop levels there.

Only 32 enemy-held U.S. troops have been recovered since the Persian Gulf War, making each one especially valuable to students learning how to evade capture if alone in hostile territory, Russell said.

Among others, Russell debriefed Michael Durant, a Special Operations pilot captured in Somalia in the 1993 "Black Hawk down" mission.

In the debrief, Durant told Russell that he owed understanding of how to conduct himself as a prisoner from stories told by Jeremiah Denton, a Navy pilot shot down and captured in North Vietnam in 1965. Denton blinked "torture" in Morse code to relay information about his treatment to U.S. authorities.