A military judge ruled Wednesday that the man accused of being the mastermind behind the 9/11 attacks will stand trial starting in June 2028.

Khalid Sheikh Mohammed will be prosecuted alongside others suspected of conspiring in the attacks: Walid bin Attash, Ali Abdul Aziz Ali and Mustafa Ahmed al-Hawsawi.

Mohammed is accused of orchestrating the plot to crash hijacked planes into the World Trade Center in New York and the Pentagon on Sept. 11, 2001. A third plane was crashed in a field in Pennsylvania during the attacks.

He has been held at the U.S. naval base at Guantánamo Bay, Cuba, since 2006.

Air Force Lt. Col. Michael Schrama, a military commissions judge, on Wednesday rejected the January 2027 start date proposed by prosecutors and instead set the trial date for about 18 months later.

The trial date was announced after a split federal appeals court last summer threw out a potential agreement that would have allowed Mohammed to plead guilty in exchange for sparing him the risk of execution.