After a confusing hearing in a US courtroom, the only man charged over the 11 September terror attacks has withdrawn a guilty plea - shortly after making it. The retraction came after US District Judge Leonie Brinkema ruled that Zacarias Moussaoui was mentally fit to enter a plea, and he proceeded to plead guilty to four of the six conspiracy charges he faces - the ones that carry the death penalty. But then Judge Brinkema explained that such a plea would mean he accepted responsibility for any involvement in the planning or execution of the attacks that left more than 3,000 dead. After a recess, the defendant withdrew his plea, quoting William Shakespeare's play Hamlet and calling upon his own interpretation of the Islamic faith. "Hamlet said: 'To be or not to be, that is the question.' I say: To plead guilty or not to plead guilty, that is the question," he told the court. "As a Muslim, I cannot endorse anything with the condition of death," he added.