THE mastermind of the 9/11 attacks, Khalid Sheikh Mohammed, is set to be charged by a military tribunal at Guantanamo along with four alleged co-conspirators, the Pentagon has said.

The suspects will be slapped with at least eight charges, including conspiracy, murder in violation of the law of war, attacking civilians, hijacking aircraft, and terrorism, said a letter notifying victims’ families.

Sheikh Mohammed, Walid bin Attash, Ramzi Binalshibh, Ali Abd al-Aziz Ali, and Mustapha Ahmed al-Hawsawi appeared before a war crimes tribunal at Guantanamo in 2008 but charges were dropped when President Barack Obama’s administration attempted to have them tried before federal civilian courts.

The Obama administration abandoned that effort last month, citing Republican opposition in Congress as it reluctantly opted to pursue justice once more before a military tribunal at the US naval base in Cuba.

Once a judge has been assigned and a panel of officers selected to form the tribunal, the accused will be arraigned within 30 days, said a letter sent out on Monday to victims’ families by the Office of Military Commissions.

“The conspiracy charge details 167 overt acts allegedly committed in furtherance of the 9/11 attacks,” the letter said.

Known in counter-terrorism circles as “KSM,” Sheikh Mohammed is the self-proclaimed architect of the September 11, 2001 attacks that killed nearly 3,000 people, and a host of other anti-Western plots.

His trial likely will face questions about evidence obtained from harsh interrogations carried out by US agents, though the military commissions operate under more lenient rules for the prosecution than a civilian court.

Sheikh Mohammed is known to have been “waterboarded” or subjected to simulated drowning 183 times during his years in US custody, a method widely recognised as torture.

He was arrested in 2003 in Rawalpindi, Pakistan and handed over almost immediately to American agents who held him in secret prisons for over three years before sending him to Guantanamo in September 2006.

In addition to felling the twin towers, he claims to have personally beheaded US journalist Daniel Pearl in 2002 with his “blessed right hand” and to have helped in the 1993 World Trade Centre bombing that killed six people.