Washington CNN  — 

Sgt. Bowe Bergdahl told the military he left his unit in eastern Afghanistan in July 2009 intending to walk to the nearest U.S. military outpost to report wrongdoing, believing he could not trust his own commanders to deal with his concerns, according to sources familiar with the Army investigation. It is the clearest indication yet of the motive behind his decision to leave his post.

Bergdahl was planning to report what he believed to be problems with “order and discipline” in his unit, a senior Defense official tells CNN. A second official says Bergdahl had “concerns about leadership issues at his base.”

This information is part of the report presented to General Mark Milley who this week decided to charge Bergdahl with desertion and misbehavior before the enemy. This information outlines what could be a key part of Bergdahl’s defense, which the army is already aware of.

Both officials declined to be identified because of the legal proceedings against Berghahl, but both have direct knowledge of the information outlined in the report. “This was a kid who had leadership concerns on his mind,” the second official said. “He wasn’t fed up, he wasn’t planning to desert.”

What Bergdahl’s concerns were, and whether they are relevant to the case of desertion the Army is trying to make will be a matter for military authorities to decide. “I can’t tell you if his concerns were valid, but in his mind they were,” the official said.

Both officials said Bergdahl believed he could make it to the next base by relying on wilderness skills he learned growing up in rural Idaho, even though the area was full of insurgents. It was not immediately clear how far the nearest base was during that timeframe in July 2009.

The first hint of what Bergdahl says his intent was came Wednesday in a 13-page letter to the Army from his civilian attorney Eugene Fidell. In that letter Fidell said that a still publicly unreleased initial Army investigation report “while hedging its bets…..basically concludes that Sgt. Bergdahl did not intend to remain away from the Army permanently.”

Read the letter

Fidell went on to say the report “also concludes that his specific intent was to bring what he thought were disturbing circumstances to the attention of the nearest general officer.” Fidell said he has received an executive summary of the initial Army report.

CNN reported last year that a British filmmaker working in Afghanistan in 2009 filmed Bergdahl and other members of his platoon in Afghanistan, showing alleged lax discipline, including the soldiers not wearing mandatory protective gear. One sergeant was demoted and three others reassigned. At that time, a U.S. official who had been briefed on the initial Army fact-finding investigation conducted in the months after Bergdahl disappeared told CNN that some of Bergdahl’s teammates said he had expressed “boredom” and thought his unit was too passive and should have been “kicking down doors,” the official said.

It is not clear how much of this information about Bergdahl’s intent was conveyed to investigators directly by Bergdahl or may have come from testimony of others. His attorney has said Bergdahl fully cooperated with them.

Fidell declined to comment beyond the details in his letter.

Bergdahl faces up to life in prison if convicted.

Romney: I wouldn’t have swapped for Bergdahl