US Defense Secretary Lloyd Austin has revoked a pre-trial agreement reached with men accused of plotting the 11 September terrorist attacks.
In a memo on Friday, Mr Austin also said he was revoking the authority of the officer overseeing the military court who signed the agreement on Wednesday.
The original deal, which would reportedly have spared the alleged attackers the death penalty, was criticised by some families of victims.
The memo named five defendants including the alleged ringleader of the plot, Khalid Sheikh Mohammed, all of whom are held in Guantánamo Bay. The original deal named three men.
“I have determined that, in light of the significance of the decision to enter into pre-trial agreements with the accused… responsibility for such a decision should rest with me as the superior authority,” Mr Austin wrote to Brig Gen Susan Escallier.
“I hereby withdraw your authority. Effective immediately, in the exercise of my authority, I hereby withdraw from the three pre-trial agreements.”
The White House said on Wednesday that it had played no role in the plea deal.
The five men named in the memo were: Khalid Sheikh Mohammed, often referred to as KSM, Walid Muhammad Salih Mubarak bin Attash, Mustafa Ahmed Adam al-Hawsawi; and two others not mentioned in the original plea: Ramzi bin al-Shibh and Ali Abdul Aziz Ali.
The men have been in custody for decades without trial. All have alleged they were tortured – KSM was subjected to simulated drowning, so-called “waterboarding”, 183 times before it was banned by the US government.
All have already faced more than a decade of pre-trial hearings, complicated by the allegations and evidence of torture against them.
Several family members of victims had criticised the terms of the deal struck on Wednesday as too lenient.
Brett Eagleson, the president of 9/11 Justice, which represents survivors and relatives of victims, had told the BBC earlier this week that the families were “deeply troubled by these plea deals”.
Terry Strada, who lost her husband Tom, told the BBC’s Today Programme: “It was a gut-punch to hear that there was a plea deal today that was giving the detainees in Guantanamo Bay what they want.”
A lawyer at Guantanamo representing Mr Mohammed told The New York Times that he was shocked by the sudden u-turn.
“If the secretary of defence issued such an order, I am respectfully and profoundly disappointed that after all of these years the government still has not learned the lessons of this case,” said lawyer Gary Sowards.
“And the mischief that results from disregarding due process and fair play.”