The Defense secretary said the group's gains had been "reversed" in some areas.
If allegations are true, it could contradict U.S. policy not to pay ransom for hostages.
While recent cases center on Americans held captive, there are key differences.
The Army says its investigation will run through September.
One book proposal depicts Bergdahl as a deserter who put American "lives in danger."
The Army sergeant on Thursday morning again faced more questioning, according to reports.
Maj. Gen. Kenneth Dahl is investigating the circumstances of Bergdahl’s disappearance.
In a 97-0 vote, lawmakers gave Robert McDonald a clear mandate to reform the agency.
Bergdahl returned to the United States last month after more than five years in captivity.
Sgt. Bowe Bergdahl's pay was halted during his years in Taliban captivity.
The senators say Reid prevented a vote that could have stopped the swap.
The soldier will continue his "reintegration process" at Brooke Army Medical Center.
He vowed to uncover more details about Obama's decision if he chairs Armed Services panel.
Executive branch must notify Congress before transferring Guantánamo Bay prisoners.
The GAO said the Pentagon violated the 2014 Defense Appropriations Act.
The investigation was due to wrap up Friday, 60 days after the Army's chief investigator was...
Feinstein has repeatedly battled the administration on a string of issues.
Army says the Miranda rights are part of regular investigative procedure.
Investigators will look into whether Bowe Bergdahl deserted his Army post in 2009.
Bergdahl's lawyer, Eugene Fidell, previously headed the National Institute of Military Justice.
The photo, taken while he was in captivity, was posted on Twitter Wednesday.
The Army said Bergdahl continues his reintegration process at Fort Sam Houston.
"Qataris are very assiduous in meeting all of those obligations," the diplomat said.
Bergdahl will arrive in San Antonio on Friday.