An American who fought with the Taliban was gaunt and dehydrated but in good condition Sunday as he recovered from a gunshot wound to his leg, a Marines spokesman said at the southern Afghan base where the man is being held. 

John Walker, 20, of Fairfax, Calif., surrendered near the northern Afghan city of Mazar-e-Sharif, where he was caught in a prison uprising before U.S. authorities took control of him and flew him here. 

CIA officer Johnny "Mike" Spann was killed in the revolt, hours after having interviewed Walker. 

Capt. Stewart Upton said Walker, who was being held as a "military detainee," was receiving intravenous fluids. He described his condition as good. 

"We want Walker out of here as quickly as possible and away from the people on the front lines who need to do the fighting," said a senior military legal adviser, who spoke on condition of anonymity. "We're just waiting until the highest authority directs us." 

Upton said Walker, under provisions of the Geneva Conventions, was being provided with shelter, food, water and medical treatment, and that the international Red Cross can monitor his treatment. 

Air Force Gen. Richard Myers, chairman of the Joint Chiefs of Staff, said Sunday that Walker has been providing useful information. He said no final decision has been made on what to do with him. 

"He's been pretty close to the action, and he has provided from the Afghan perspective some useful information," Myers said on Fox News Sunday. "I think the evidence is pretty strong that he was right in the middle of it." 

Vice President Dick Cheney, speaking on NBC's Meet the Press, said: "Somebody will have to make a decision whether he needs to be brought to trial, what the charge might be." 

Pentagon officials said Walker would be handed over to civilian authorities, but the timing of the transfer and exactly where Walker would go were not clear. 

In San Francisco, James Brosnahan, a lawyer for Walker's parents, declined comment. 

Marines also worked Sunday to build a detention center for prisoners of war just outside the walls of their desert camp. Marines spokesman Capt. David Romley said the camp will house any battlefield detainees or prisoners of war — or even civilians — that U.S. military officials want to hold in Afghanistan. 

Any other detainees would have the same rights as Walker, Romley said. 

At the site where the detention center was being built, a watch tower overlooks a pen with a nine-foot berm. Barbed wire lies on the ground, presumably to string around the perimeter. 

The Justice Department has said Americans who have fought for the Taliban or Al Qaeda could face treason, murder, conspiracy or other charges. 

Walker's parents have described him as an introvert and pacifist who converted to Islam when he was 16. He studied in Yemen and Pakistan, but his parents lost contact with him about six months ago. 

Through their attorney, Frank Lindh and Marilyn Walker, said Friday they are "desperately worried" about their son. 

They also said the government had not given them any word about his their son's condition or whereabouts. 

Meanwhile, the Marines continued to dig fighting holes around their base, which they man 24 hours a day despite temperatures that drop below freezing at night. 

"My mother is very proud of what I'm doing, but also scared to death," said Lance Cpl. Phillip Constantine, 20, of New Baeden, Ill. "So far it's going very smooth." 

Lance Cpl. Carlos Romero, 23, of Long Beach, Calif., missed the birth of his daughter two months ago. But he said it was for a good cause. 

"For us, when they say go, we go," he said. "We always expect to be in the thick of things."