The U.S. government has successfully blocked an alleged 9/11 terrorist attacks mastermind from pleading guilty due to disputed terms of a pretrial agreement.

Khalid Sheikh Mohammed and two co-defendants struck a deal last summer to plead guilty to all charges in exchange for not facing a death penalty trial.

In papers filed with a federal appeals court, the government argued it would be irreparably harmed if the request were accepted.

The three-judge panel said they needed more time to consider the case and suspended proceedings. They stressed that the delay “should not in any way be construed as a ruling on the merits of the case.”

This comes after a military judge and appeals panel rejected a previous motion by Defense Secretary Lloyd Austin Withdrawal from agreementsigned by a senior official appointed by him.

The attacks of September 11, 2001, killed nearly 3,000 people 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.

The three men have been in U.S. custody for more than 20 years, and pretrial hearings in the case have lasted for more than a decade.

The dispute centers on whether the evidence was tainted by torture the defendants endured while in CIA custody after their arrest.

After his arrest in 2003, Muhammad was subjected to 183 simulated drownings or “waterboarding” while held in a secret CIA prison. Other so-called “advanced interrogation techniques” included sleep deprivation and forced nudity.

Some family members of those killed in the 9/11 attacks have criticized the protocols as being too lax or lacking transparency, while others see them as a way to move the complex and long-running case forward.

Those who had traveled to the U.S. naval base at Guantanamo Bay, Cuba, to watch Mohammed’s confession were speaking to reporters when the postponement was announced.

“The U.S. government has once again failed the 9/11 families. They had a chance to do the right thing but decided not to,” said Tom Resta, whose brother, sister-in-law and unborn child are among the Killed in the attack.

The government argued that going ahead with the deals would mean it was denied the opportunity to “seek the death penalty against three men accused of a heinous act of mass murder that left thousands dead and shocked the nation and the world.”

“In this important case, a brief delay to allow the court to weigh the reasonableness of the government’s request will not cause substantial harm to the defendants,” the statement said.

Mohammed’s team said in response that the agreement provided “the first opportunity for real closure” in nearly a quarter of a century. The statement said the two-year plea negotiations “directly involved the White House.”

In its ruling Thursday night, the federal appeals court said its ruling was intended to give the justices time to be fully briefed and hear arguments “quickly.”

The delay means the matter will now fall to the incoming Trump administration.

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

At a court hearing in Guantanamo on Wednesday, his legal team confirmed he had agreed to plead guilty to all charges.

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.