BOISE - The top U.S. commander in Afghanistan on Sunday issued a statement marking four years that a U.S. solider has been held captive by the Taliban.

U.S. Army Sgt. Bowe Bergdahl, 27, of Hailey, is the only known American soldier held captive from the Afghan war. He disappeared from his base in southeastern Afghanistan on June 30, 2009, and is believed held in Pakistan.

"Four years later, we are still waiting for Sgt. Bergdahl's safe return, and it is my sincere hope that the wait will soon come to an end," Marine Gen. Joseph Dunford said. "To Sgt. Bergdahl's family, I want to say that we know you have not given up hope, and neither have we."

Col. Tim Marsano with the Idaho National Guard has been acting as media liaison for Bergdahl's family. Marsano said on Sunday that the family wasn't available for comment.

But Bergdahl's parents spoke June 22 at a rally in Hailey, in central Idaho, that drew about 2,000 people, including hundreds of motorcycle riders. His mother, Jani Bergdahl, said the family was feeling optimistic after his Taliban captors offered earlier this month to exchange him for prisoners at Guantanamo Bay. Bob Bergdahl accompanied the motorcycle procession that day on his son's 1978 dirt bike.

"I understand the people of Hailey, Idaho, continue to remember Sgt. Bergdahl this year by planting a tree and hosting a 500-bike motorcycle ride," Dunford said. "Our thoughts and prayers are with them and would like nothing more than to see him returned to his loved ones."

Bergdahl is assigned to the 1st Battalion, 501st Infantry Regiment, 4th Brigade Combat Team, 25th Infantry Division, from Fort Richardson, Alaska