The first appearance of five leading 9/11 suspects before a military tribunal at the US base at Guantanamo Bay has been marked by hectic scenes.
Khalid Sheikh Mohammed and four others accused of plotting the 2001 attacks refused to respond to questions during the seven-hour hearing.
One launched into a defiant outburst, suggesting the Americans might kill him before the end of the trial.
The five refused to enter pleas on murder and terrorism charges.
The charges, over the attacks in which 2,976 people died, can carry the death penalty.