US Supreme Court snubs bid to revive plea deal for accused 9/11 mastermind

Mohammed remains the most well-known inmate at the Guantanamo detention facility, which was set up in 2002 by then-US president George W. Bush to house foreign ⁠terrorism suspects ​following 9/11.

The US Supreme Court declined on Monday to hear a bid by Khalid Sheikh Mohammed, the accused mastermind of the September 11, 2001, attacks, to revive a 2024 agreement that would have spared him the death penalty in exchange for a guilty plea - a deal scrapped by former Defense Secretary Lloyd Austin.

The justices turned away appeals by Mohammed and two co-defendants who had also signed plea agreements of a lower court's ruling that upheld Austin's decision to void the deals. The US Court of Appeals for the District of Columbia Circuit rejected an argument that Austin, who served under former US president Joe Biden, had acted too late.

The Supreme Court's action marks the latest milestone in a military prosecution of the detainees held in Guantanamo Bay, Cuba, that has been beset by two ⁠decades of legal gridlock.

In August, a US Air Force judge set the trial for Mohammed and his co-defendants for June 2028.

Mohammed remains the most well-known inmate at the Guantanamo detention facility, which was set up in 2002 by then-US president George W. Bush to house foreign ⁠terrorism suspects ​following the 9/11 attacks, which killed nearly 3,000 people. Mohammed is accused of orchestrating the plot ​to fly hijacked passenger jetliners into the World Trade Center in New York City and into the Pentagon in Arlington, Virginia.

Mohammed, co-defendants accepted agreement before deal revoked

The plea agreements for Mohammed and co-defendants Mustafa al Hawsawi and Walid bin 'Atash had been offered and accepted by the US official overseeing the Pentagon's Guantanamo war court, prompting criticism by Republican lawmakers.

Austin revoked the deals two days later.

A military judge ruled that Austin lacked authority to invalidate the plea deals in a decision that was upheld in December by the US Court of Military Commission Review. The judge then scheduled prompt plea hearings.

The DC Circuit paused those proceedings, and in July 2025, a panel of that court - in a 2-1 vote - backed the decision to scrap the plea deals, saying that Austin "indisputably had legal authority to withdraw from the agreements."

Defense attorneys for Mohammed and al Hawsawi, including lawyers from the American Civil Liberties Union, urged the Supreme Court to hear the case. They said Austin's action violated controlling military law and "prolonged the best chance for finality in the September 11 case in a quarter century."