Army Sgt. Bowe Bergdahl is due back in court for a pretrial hearing on the charges he faces after walking off a post in Afghanistan in 2009.

The hearing Thursday is likely to include a discussion of defense efforts to gain access to the correspondence of high-ranking military officials who were in positions of authority when Bergdahl's disappearance unfolded.

Defense lawyers argue in recent motions that the correspondence could show whether improper influence was exerted. Prosecutors say the efforts are speculative and unwarranted.

Bergdahl, who's from Hailey, Idaho, faces charges of desertion and misbehavior before the enemy after walking off his post and winding up in enemy captivity for five years. The Obama administration was criticized for swapping Guantanamo Bay detainees for Bergdahl.

His military trial is tentatively scheduled to start in early 2017.