Khalid Sheikh Mohammed is seen in this March 1, 2003 file photograph.

WASHINGTON, Dec. 8 (Xinhua) -- The Pentagon said Monday that five detainees at U.S. Naval base in Guantanamo Bay, Cuba, want to confess to conspiracy charges for planning the 9/11 attacks.

Khalid Sheikh Mohammed, the "architect" of the attacks, and four co-conspirators asked a military judge if they could withdraw all pending motions and plead guilty, Pentagon spokesman Gail Crawford told reporters.

The judge accepted the request but ruled that "competency hearings" are first needed for two of the five, Mustafa al Hawsawi and Ramzi bin al Shibh, because "questions exist as to their competency to stand trial," he said.

Meanwhile, Denis McDonough, a senioradviser to President-elect Barack Obama, told media that no decisions have been made by Obama about what to do with the 255 inmates presently held at Guantanamo.

"There is no process in place to make that decision until Obama's national security and legal teams are assembled," he said.

Sources close to Obama team said the incoming administration is considering putting some of the inmates on trial in existing federal courts, setting up a special national security court to deal with cases involving sensitive intelligence, and releasing other inmates.