The alleged mastermind of the 9/11 terror attacks in the United States will not plead guilty on Friday after the U.S. government moved to block a plea deal reached last year from going forward.

Khalid Sheikh Mohammed, commonly known as KSM, will make his plea at a war tribunal at the Guantanamo Bay naval base in southeastern Cuba, where he has been held at the military prison for nearly two decades.

Muhammad was the most notorious detainee at Guantánamo and one of the last people to be held at the base.

But late Thursday, a federal appeals court paused the scheduled proceedings to consider the government’s request to abandon the plea deal, saying it would cause “irreparable” harm to the government and the public.

The three-judge panel said the delay “should not be construed in any way as a ruling on the merits” but was intended to give the court time to hear full briefs “expeditiously” and hear arguments.

The delay means the matter will now be handled by the incoming Trump administration.

At a hearing that begins Friday morning, Muhammad plans to plead guilty to his role in the attacks of Sept. 11, 2001, when hijackers hijacked passenger planes and crashed them into the World Trade Center in New York and the Pentagon outside Washington. Another plane crashed into a Pennsylvania field after passengers fought back.

Mohammed was charged with conspiracy and murder, with 2,976 victims listed on the charge sheet.

He has previously said he planned the 9/11 operations “from start to finish” – envisioning training pilots to fly commercial planes into buildings – and presented those plans to Osama, the leader of the radical Islamist group Islamic State. Bin Laden. Al Qaeda, mid-1990s.

Friday’s hearing is scheduled to be held in the base’s courtroom, where families and media will sit on a viewing platform behind thick glass.

Pretrial hearings at the naval base’s court-martial have continued for more than a decade, complicated by the question of whether the torture Muhammad and other defendants endured while in U.S. custody tainted evidence.

After being captured in Pakistan in 2003, Muhammad spent three years in secret CIA prisons known as “black sites,” where he was subjected to 183 simulated drownings or “waterboarding,” as well as other so-called “advanced” interrogation techniques,” which included sleep deprivation and forced nudity.

Karen Greenberg, author of “The Least Worst Place: How Guantanamo Became the World’s Most Notorious Prison,” said the use of torture makes it “nearly impossible to prosecute these cases in a way that respects the rule of law and American jurisprudence.” conduct a trial.”

“It is clearly impossible to produce evidence in these cases without the use of evidence of torture. Furthermore, the fact that these individuals were tortured adds to the complexity of the prosecution,” she said.

The case also falls under the jurisdiction of a military commission, which operates under different rules than the traditional U.S. criminal justice system, slowing down proceedings.

The plea deal was reached last summer after about two years of negotiations.

Full details of the deal with Mohammed and his two co-defendants have not been released.

We do know that the deal means he will not face a death penalty trial.

At a court hearing on Wednesday, his legal team confirmed he had agreed to plead guilty to all charges. Mohammed did not address the court in person but instead discussed the agreement with his team, working with prosecutors and the judge to make minor corrections and revisions to the wording.

If the agreement is upheld and the court accepts the request, the next step will be to appoint a military jury, known as a panel, to hear evidence at a sentencing hearing.

In court Wednesday, lawyers described it as a form of public trial in which survivors and families of the victims would have a chance to make statements.

According to the agreement, the family can also ask questions of Mohammed, who must “answer their questions fully and truthfully,” the lawyer said.

Central to prosecutors’ agreement to the deals was the assurance that “we can present all the evidence that we deem necessary to establish the history of the defendant’s involvement in the events of September 11,” prosecutor Clayton G. Trivett Jr. said. , said in court Wednesday.

Even if the guilty pleas proceed, it will take several months for proceedings to begin and ultimately for sentencing to be pronounced.

U.S. Defense Secretary Lloyd Austin named the top officials who signed the agreement. But he was traveling when the deal was signed, and he was reportedly surprised, according to The New York Times.

Days later, he tried to reverse the decision, saying in a memo: “Responsibility for such a decision rests with me as the higher authority.”

However, both a military judge and a military appeals panel ruled that the agreement was valid and that Mr. Austin acted too late.

In another attempt to block the deal, the government this week asked a federal appeals court to intervene.

In a legal filing, it said Muhammad and two other men were accused of “committing one of the most egregious crimes in modern history on U.S. soil” and that enforcing the agreements would “deprive the government and the American people of any The opportunity for a public trial “despite the fact that the Secretary of Defense has legally withdrawn from these agreements, the defendants’ guilt and the possibility of the death penalty.”

After the deal was announced last summer, Republican Senator Mitch McConnell, then the party’s leader in the House of Representatives, issued a statement calling it a “disgusting abdication of the government’s responsibility to defend America and deliver justice.”

Some family members of those killed in the attack also criticized the agreement, saying it was too lax or lacked transparency.

Terry Strada, whose husband Tom was killed in the attack last summer, told the BBC’s Today program that the deal “gave the detainees at Guantanamo Bay what they wanted” something”.

Ms Strada, national president of the campaign group 9/11 Families United, said: “This is a victory for Khalid Sheikh Mohammed and the other two, a victory for them.”

Other families see the agreements as a path to conviction in complex and lengthy proceedings and are frustrated by the latest government intervention.

Stephen Gerhardt, whose brother Ralph was killed in the attack, flew to Guantanamo Bay to watch Mohammed confess.

“What is the ultimate goal of the Biden administration? So they get a reprieve and this drags on to the next administration. What is the purpose? Think about those families. Why are you prolonging this saga?” he said.

Mr Gerhardt told the BBC the deals were “not a victory” for the families but it was “time to find a way to end this and convict these people”.

Family members at the base were meeting with the media when news of the delays became public.

“This was supposed to be a moment of healing. We were going to get on that plane with that deep pain – there was no end to that pain,” one said.

Mohammed has been held in the military prison at Guantanamo Bay since 2006.

The prison opened 23 years ago (January 11, 2002) during the “war on terror” following the 9/11 attacks as a place to hold terror suspects and “unlawful enemy combatants.”

Most of those held here have never been charged, and the military prison has been criticized by human rights groups and the United Nations for its treatment of detainees. Most have now been repatriated or resettled in other countries.

The prison currently houses 15 inmates, the smallest number in the prison’s history. All but six have been charged or convicted of war crimes.