In their most detailed response to US war crimes charges, the five Guantanamo prisoners justified the attack that killed nearly 3,000 people.
They included self-proclaimed mastermind Khalid Sheik Mohammed.
According to CBS, in an extraordinary six-page filing with the Military Commissions in Guantanamo Bay, Cuba, Mohammed and the four others took full responsibility for the attacks and refuted the nine accusations against them, point-by-point.
The five men are charged with conspiracy. To that they respond, "This is a very laughable accusation. Were you expecting us to inform you about our secret attack plans?"
As for charges al Qaeda targeted civilians, they accuse the United States of "...attacking us in Palestine and Lebanon..." And they ask, "...was it not you that attacked an entire population in Iraq..."
They label themselves tortured prisoners, and chide the United States saying, "You have no values and ethics and no principals."
President Barack Obama suspended their trial in January as his administration evaluates the war crimes trials.
Meanwhile, alleged al Qaeda sleeper agent Ali al-Marri appeared in a US court on Tuesday, Mar 11 to face terror charges for the first time after being held for more than five years as an enemy combatant.
Al-Marri is charged with providing material support to terror and conspiracy and is expected to be sent to Illinois to enter a plea.