After two decades at Guantánamo Bay, trials for four alleged 9/11 conspirators have been set for 2028.

A US military judge has ordered Khalid Sheikh Mohammed, the alleged mastermind of the September 11 attacks, and three co-defendants to stand trial, more than two decades after their arrest.

Air Force Lieutenant Colonel Michael Schrama issued the scheduling order on Wednesday, setting opening proceedings for June 5, 2028.

The ruling comes after a US appeals court blocked plea deals that would have let Mohammed and two co-defendants avoid the death penalty.

The case has been stalled for years by disputes over evidence obtained while the men were held in CIA prisons and subjected to torture.

Schrama turned down a prosecution bid to open the trial in early 2027, arguing that timeline wouldn’t leave enough room to work through the disputes.

“A realistic trial date must account for the hearing and resolution of pretrial evidentiary and compliance motions,” he wrote.

Mohammed faces trial along with Walid bin Attash, Mustafa al-Hawsawi and Ali Abdul Aziz Ali.

Under the order, a jury of military service members will first be selected, with opening statements to follow 30 days later. The defence is due to begin presenting its case 60 days after prosecutors finish theirs and the trial will close with a sentencing phase.

Mohammed and two of his co-defendants struck a deal in 2024 that would have spared them the possibility of the death penalty in exchange for a guilty plea.

Then-Defense Secretary Lloyd Austin revoked that deal within days and an appeals court backed his move last month.

Mohammed was regarded as one of al-Qaeda chief Osama bin Laden’s key lieutenants until he was captured by US forces in Pakistan in March 2003. He spent three years in secret CIA prisons before arriving in Guantanamo in 2006.