KESI YA WALIO PANGA MASHAMBULIZI YA SEPTEMBER 11: Defiance of a monster: 9/11 mastermind refuses to answer to judge as his Guantanamo trial for 2,976 murders begins

Captured: Khalid Sheikh Mohammed and four co-defendants are to be arraigned at a military tribunal at Guantanamo Bay on charges including 2,976 counts of murder

The self-proclaimed mastermind of the Sept. 11 attacks declined to respond to a judge's questions Saturday and his co-defendant was briefly restrained at a military hearing as five men charged with the worst terror attack in U.S. history appeared in public for the first time in more than three years.

Khalid Sheikh Mohammed and his co-defendants appeared for arraignment at a military tribunal at Guantanamo Bay on charges that include 2,976 counts of murder for the 2001 attacks.

The hearing quickly bogged down before they could be arraigned. 

Mohammed repeatedly refused to respond to questions from the judge, Army Col. James Pohl while prisoner Walid bin Attash was put in a restraint chair for unspecified reasons and then removed from it after he agreed to behave.

The families of six victims killed in the attacks are at court witnessing the trial while other victims' families are able to watch the trial through close-circuit TV.

Lawyers for all defendants complained that the prisoners were prevented from wearing the civilian clothes of their choice.

Mohammed wore a white turban in court; his flowing beard, which had appeared to be graying in earlier hearings and photos, was streaked with red henna.