American Taliban John Walker Lindh arrived back in the United States late Wednesday under FBI custody to be formally charged in a federal courtroom Thursday morning with conspiring to kill his fellow Americans.

Walker, the 20-year-old Californian captured fighting with the Taliban in Afghanistan, landed in a military cargo plane at Dulles International Airport, just outside Washington, D.C., said a law enforcement official, speaking on condition of anonymity. The plane, with a large American flag painted on its tail, landed on one of the airport's primary runways.

A four-car motorcade greeted Walker's helicopter and took him to an Alexandria detention center.

Walker has a 9 a.m. EST initial court appearance scheduled for Thursday in this Washington suburb not far from the Pentagon to answer to charges of conspiracy, providing material support to terrorists and engaging in prohibited transactions with the Taliban.

Attorney James Brosnahan said Walker has a four-member defense team including himself. Brosnahan said in a statement that Walker's parents received a letter from their son Wednesday that was dated Jan. 8 and "penned by a member of the U.S. military."

The lawyer quotes Walker as stating, "It is comforting to know that you have found a lawyer." The letter then refers to Brosnahan.

Another member of the defense team, William Cummings, told ABC News he wants to get interviews Walker gave the FBI thrown out, because no lawyer was present and Walker — who was wounded — was in no physical condition to understand what was happening.

Walker's parents, Marilyn Walker and Frank Lindh, who are from the San Franciso area, went to the Alexandria jail Wednesday night with attorneys in hopes of meeting with their son. But they emerged after about a half-hour saying they had been unable to see him.

"We're a little disappointed, but the guard was able to tell us that he is in good condition," Lindh said of his son. Brosnahan said jail authorities felt the meeting should be put off until Thursday.

Back on his native soil two years after he left the United States for Yemen to study Arabic and Islam, Walker could spend the rest of his life in prison if convicted of the charges brought against him.

"We're prepared for every possible contingency," said John Hackman, deputy chief U.S. marshal for the federal district, who confirmed the schedule for Thursday's hearing. U.S. Magistrate Judge W. Curtis Sewell will preside.

Hackman would not reveal where Walker would be held overnight, but said, "He'll be in a safe and secure and humane area."

Walker was taken off the USS Bataan warship in the Arabian Sea by helicopter and transferred to another military plane at the airport at the southern Afghan city of Kandahar, officials said.

The Pentagon would not officially confirm the transfer, saying it would be dangerous to release any information about his movements. Journalists were kept away from the area at Kandahar where Walker boarded the plane.

Walker's flight was probably similar to those of the detainees taken to Guantanamo Bay, Cuba. In those flights, the detainees were bound at the wrist with handcuffs and tape and wore blacked-out goggles.

"When people are moved, they are restrained," Defense Secretary Donald H. Rumsfeld said Tuesday. "It is not anything new. It is because in transit, movement from one place to another, is the place where bad things happen."

The FBI alleges in court papers that Walker in June became a foot soldier for Usama bin Laden, who thanked him personally for "taking part in jihad," or holy war. The FBI also claims Walker learned within weeks of joining bin Laden about suicide teams being sent to America. Those allegations are largely based on statements Walker made to investigators during two days of interviews in December, when Walker waived his rights to speak with a lawyer.

"Terrorists did not compel John Walker Lindh to join them," U.S. Attorney General John Ashcroft said. "John Walker Lindh chose terrorists. Our American system of justice will allow Walker the rights and due process that the terrorists he fought side by side with sought, and still seek, to destroy."

White House spokesman Ari Fleischer said Wednesday that President Bush believes that Walker "will now get the justice he deserves." Fleischer called the criminal charges against Walker "extraordinarily serious."

"He will now have his day in court and he will be judged impartially and fairly," Fleischer said.

In an interview aired Wednesday on NBC Nightly News, Bush said he decided "for a variety of reasons" against trying Walker for treason, adding, "I also am pleased that he's going to be afforded a chance to make his case in a court of law."

First lady Laura Bush expressed sympathy for Walker's parents. "I'm sure his parents are unbelievably crushed and, you know, worried and sick, everything that every parent feels when their children have a problem like he has," she said.

The interview, conducted as part of an NBC special on the Bush White House, was taped prior to Walker's return from Afghanistan.

At Thursday's hearing, the U.S. magistrate will announce the charges against Walker and ensure that he has a lawyer. The next step would be a detention hearing where bail conditions would be set. The case would then go to a federal grand jury.

The Associated Press contributed to this report.