GUANTANAMO BAY NAVAL BASE, Cuba - Khalid Sheikh Mohammed, appearing for the first time since his capture five years ago, said he would welcome becoming a "martyr" after a judge warned yesterday that he faces the death penalty for his confessed role as mastermind of the Sept. 11 terrorist attacks.

Mohammed chanted verses from the Quran, rejected his attorneys and told Judge Ralph Kohlmann, a Marine colonel, that he wants to represent himself at the war crimes trial.

The judge warned that he faces execution if convicted of organizing the attacks on America. But the former No. 3 leader of al Qaeda was insistent.

"Yes, this is what I wish, to be a martyr for a long time," Mohammed declared. "I will, God willing, have this, by you."

Mohammed and his four alleged co-conspirators each face death if convicted of war crimes including murder, conspiracy, attacking civilians and terrorism by hijacking planes to attack U.S. landmarks. The murder charges involve the deaths of 2,973 people at the World Trade Center, Pentagon and a field in Pennsylvania where passengers forced down their plane.

Their arraignment begins the highest-profile test yet of the military's tribunal system, which faces an uncertain future. The Supreme Court is to rule this month on the rights of Guantanamo prisoners, potentially delaying or halting the proceedings.

The trial also carries some strategic risk, and the military is trying to minimize the chance that classified information that would endanger Americans will come out, including delaying closed-circuit video of the proceedings by 20 seconds.

Mohammed seemed calm for the most part, but became upset and denounced the tribunals as unfair after the judge told defense lawyers to be quiet and "sit down!"

"It's an inquisition. It's not a trial," Mohammed said, his voice rising. "After torturing they transfer us to inquisition land in Guantanamo."

The five men, sitting at separate tables, spoke with each other in Arabic, appeared to pass notes to each other and at one point looked back and chuckled at reporters watching from behind a courtroom window.

None wore handcuffs, but the ankles of Ramzi Binalshibh, said to have been the main intermediary between the hijackers and al Qaeda leaders, were shackled to the courtroom floor. *