GUANTANAMO BAY, Cuba — Khalid Sheik Mohammed, the self-proclaimed mastermind of the September 11, 2001, terrorist attacks, yesterday appeared publicly for the first time since his capture five years ago and calmly told a U.S. military court that he hopes for a death sentence that will allow him to die “a martyr.”

Sitting at the front of a line of five detainees accused of carrying out the most devastating terrorist attack in American history, Mohammed stroked his long, bushy, gray beard, and spoke in confident English of his contempt for the American Constitution and the military commissions designed to try him.

Calling the process an “inquisition,” Mohammed told Marine Colonel Ralph Kohlmann, the presiding judge, that he wants to represent himself at trial and looks forward to the death penalty.

“Yes, this is what I wish,” Mohammed said, toying with his eyeglasses. “I have (been) looking to be a martyr from long time. I will, God willing, have this, by you. I understand very well.”

Clad in white tunics and turbans, Mohammed and four other alleged top Al Qaeda operatives emerged yesterday morning from the shadows of their lengthy U.S. detention to face arraignment in one of the most anticipated trials in American history. The men, alleged to be at the heart of the terrorist conspiracy that shook America on September 11, are charged with orchestrating the deaths of thousands of Americans on airplanes, in New York skyscrapers and at the Pentagon.

The government case is largely designed to obtain death sentences against them. Even acquittal likely would leave the men in American custody indefinitely. The American government has determined them to be “enemy combatants” and serious threats to America and its allies.

Yesterday’s arraignment is just the first step in what is certain to be a lengthy and contentious legal process, one that likely will put the untested military commissions system itself on trial. The chief legal adviser for the military commissions, Air Force Brigadier General Thomas Hartmann, argued that the trials will be “fair, just, and transparent,” but defense lawyers have said that the system is a sham and that justice cannot be pursued in the courtrooms of this island military base.

Mohammed, appearing as leader and elder statesman of the group, quickly took center stage at yesterday’s hearing, railing against President Bush and his “crusades” in Iraq and Afghanistan. He appeared to orchestrate a last-minute strategy that could prove a major disruption to the military commission trials.