U.S. Army Sgt. Bowe Bergdahl took the stand at his sentencing on Monday, apologizing to the troops who got hurt searching for him after he deserted in Afghanistan in 2009 and detailing the harsh conditions of Taliban captivity.

"I made a horrible mistake," the 31-year-old soldier said during his most extensive comments to date at North Carolina's Fort Bragg. "Saying I'm sorry is not enough."

His statements marked the opening of the defense's case, which suffered a blow earlier in the day when the presiding military judge said President Donald Trump had not damaged Bergdahl's chances of a fair sentence.