TOKYO — The White House's top lawyer is returning to private practice and being replaced by a longtime adviser to Barack Obama.

White House counsel Greg Craig, who's leaving in early January, has been the subject of repeated questions about his future since late summer. Centered on talk that Obama's promise to close the Guantanamo Bay military prison by January had gone awry under Craig's leadership, the questions were settled Friday when the White House announced Craig's departure.

It was the highest-ranking resignation so far in Obama's 10-month presidency, and became public just as the president was arriving in Asia for a weeklong tour. It also came just hours before Attorney General Eric Holder was set to announce that self-proclaimed Sept. 11 mastermind Khalid Sheikh Mohammed and four other Guantanamo Bay detainees will be sent to New York to face trial in a civilian federal court, while five other suspects will be prosecuted in military commissions. This was revealed to The Associated Press by an Obama administration official earlier Friday.

Craig also oversaw the president's revamping of U.S. policy on terrorism interrogations and detentions, including a ban on torture, and was at the center of administration moves to release many documents relating to the treatment of terror suspects under the Bush administration. He also was instrumental in the White House's decision to resist the release of photos of abuse of detainees overseas by U.S. personnel. All those decisions earned Obama considerable criticism, some from the right and some from the left.

Obama issued a statement praising Craig as a trusted adviser who took on numerous difficult challenges, including the selection and confirmation of Supreme Court Justice Sonia Sotomayor.

"I'm indebted to Greg not only for leading the counsel's office but for his many decades of service to this country as well. He has been a huge asset in the White House, and he will be missed," the president said. "I will continue to call on him for advice in the years ahead."

White House press secretary Robert Gibbs said Craig's departure was not due to any dissatisfaction with his handling of Guantanamo policy. Craig was known to have told Obama at the outset that he didn't want to serve in the counsel role for more than a year.

Still, Craig's resignation falls more than two months short of that milestone. It had been presumed that he would move from the counsel's office to another prestigious job, such as an ambassadorship or judicial posting, but the White House statement mentioned only his return to private legal work.