GUANTANAMO BAY NAVAL BASE, Cuba — Three Sept. 11 defendants took a judge up on his offer to let them skip their military tribunal Tuesday and the proceedings went on without them. The Guantanamo detainees won a new request to return to court in camouflage clothing if they wanted.

Khalid Sheikh Mohammed, the self-professed 9/11 mastermind, was not in the courtroom while attorneys delved into a dense debate on legal motions, including rules for handling classified evidence at trial and what kind of clothing would be allowed.

Only two of the five defendants made it to court for the second day of the weeklong hearing. Mohammed, Saudi defendant Mustafa Ahmad al-Hawsawi and Pakistani national Ali Abd al-Aziz Ali — Mohammed’s nephew — all stayed away.

The presiding judge, Army Col. James Pohl, ruled Monday that the defendants didn’t have to attend the hearing every day this week, although he said they would have to attend their formal trial and may need to attend future hearings.

Mohammed was taken from his cell at the U.S. base in Cuba to a holding cell outside the courtroom, then chose to boycott at the last minute, said a Navy officer whose name was not released by the court for security reasons.

The 47-year-old Mohammed, who has previously said he conceived and orchestrated the Sept. 11 attacks, gave no reason for sitting out the hearing. But on Monday, he dismissed the military tribunal with scorn, saying “I don’t think there is any justice in this court.”

Authorities have portrayed the other defendants as Mohammed’s underlings, who provided logistical and other help to the Sept. 11 hijackers.