A United States military appeals court has denied an effort by Pentagon chief Lloyd Austin to throw out possible plea deals for the alleged mastermind of the attacks on September 11, 2001, and his two co-conspirators.

The deals could see the three men ? Khalid Sheikh Mohammed, Walid bin Attash and Mustafa al-Hawsawi ? plead guilty to the attacks, which killed nearly 3,000 people. In exchange, they would be spared the possibility of the death penalty.

A plea hearing for Mohammed, who is accused of orchestrating the killings, is set for next week.

The New York Times and Associated Press both reported on Monday night that the military appeals court had ruled against Austin.

The decision upheld a previous judgement from a military judge, Colonel Matthew McCall, who ruled that Austin lacked the standing to throw out the plea bargains following their initial approval.

News of the possible plea deals emerged several months ago. They signalled a possible off-ramp for a case long complicated by the use of torture on prisoners swept up during the so-called ?global war on terror?, launched by the US in the wake of the September 11 attacks.

Legal experts have said that the use of torture ? dubbed ?enhanced interrogation? by the administration of former President George W Bush ? could prolong or prevent a conviction.

For instance, revelations that Majid Khan, a former al-Qaeda courier, had been tortured at a Central Intelligence Agency (CIA) black site prompted public outcry. The CIA denied the allegations, but Khan?s lawyers described him suffering sexual abuse, starvation and waterboarding.

In 2021, a military jury, composed of eight officers, sentenced Khan to 26 years in prison, the shortest sentence possible. But seven of the eight members on the panel urged the government to offer clemency, given the nature of Khan?s torture.

Like Khan and other September 11 defendants, Mohammed and the two other defendants are being tried by a special military commission set up under World War II-era laws that allow for the prosecution of foreign defendants outside of the US justice system.

While a Pentagon appointee had initially signed off on the plea deals, Austin sought to revoke the agreements in August amid pressure from lawmakers and family members of victims, who deemed the deals too lax.

Austin later said he believed Americans deserved the opportunity to see the trials through.

Defence lawyers, however, charged that Austin?s push to revoke the plea deals represented unlawful interference in the case.

Despite Monday?s decision, Austin can still appeal the case to the US Court of Appeals for the District of Columbia Circuit, which could cause further delays.

Years of hearings

Pre-trial hearings for the three men in the case and a fourth defendant, Ammar al-Baluchi, have stretched for more than a decade. Unlike his three co-defendants, al-Baluchi has not agreed to plea-deal negotiations.

All four of the accused have been held at the Guantanamo Bay detention centre in Cuba.

The military prison has become a lasting symbol of US abuses in the wake of the September 11 attacks, with dozens of detainees continuing to be held there without the rights guaranteed under US law.

The administration of US President Joe Biden had entered office hoping to close the facility for good, but it remains open as President-elect Donald Trump prepares to take office on January 20.

Once holding 800 detainees, the Guantanamo Bay facility housed approximately 40 people when Biden took office in 2021.

Several have since been transferred to second countries, including four in the last two weeks.

One of those includes Tunisian detainee Ridah bin Saleh al-Yazidi. On Monday, the Pentagon announced he had been repatriated to Tunisia.

Despite being approved for a transfer more than a decade ago, al-Yazidi was kept in the Guantanamo facility for years, as no agreement had previously been reached with Tunisia?s government.

Al-Yazidi, a suspected member of al-Qaeda, had never been charged after being detained in Pakistan near the Afghan border in 2001.

According to the Pentagon, 26 people remain incarcerated in the Guantanamo Bay centre. Of that group, 14 are eligible for a transfer. (Al Jazeera and News Agencies)

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