Khalid Sheikh Mohammed and two accomplices, Walid Bin Attash and Mustafa al-Hawsawi, were expected to plead guilty at the military commission on Guantanamo Bay base as early as next week.
In exchange, they would avoid the risk of the death penalty and instead be sentenced to life imprisonment, which emerged in a letter sent to families of the nearly 3,000 people killed in the terrorist attacks.
However, Defense Minister Austin is now said to have withdrawn the offer of an agreement.
"The responsibility for such a decision rests with me," Austin writes in a press release addressed to Susan Escallier, who oversees the trial in the military court at Guantanamo Bay, according to AFP.
He further writes that he is withdrawing the agreements that Escallier signed regarding the three men.
Several families of the attack victims have condemned the agreement. Republicans were also quick to criticize the Biden administration, but the White House has claimed that they had no knowledge of the agreements.
The three men were arrested in 2003 and are being held at Guantanamo Bay. The protracted legal process has been affected by the question of whether the torture they were subjected to in CIA custody has affected the evidence.
It has been over 16 years since the prosecution process for al-Qaeda's terrorist attacks began – and more than 20 years after terrorists took over commercial airliners and crashed them into the World Trade Center in New York and the Pentagon. Nearly 3,000 people died in the attacks.