Khalid Sheikh Mohammed will appear in a Guantanamo Bay courtroom this week, more than 18 years after the 9/11 terrorist attacks he is alleged to have masterminded and a year before he will finally face a jury. In the nearly two decades since 19 al Qaeda terrorists crashed hijacked planes into the World Trade Center buildings, the side of the Pentagon, and a field near Shanksville, Pennsylvania, killing nearly 3,000 people, the five men believed to be responsible have yet to face a trial.