The Supreme Court is leaving in place a decision that the alleged mastermind of the 2000 attack on the USS Cole that killed 17 U.S. sailors should face a trial by a military commission.

The court on Monday declined to take up the case of Saudi national Abd al Rahim al-Nashiri. Al-Nashiri had sought to challenge the authority of a military commission in Guantanamo Bay hearing his case. But an appeals court ruled last year that al-Nashiri’s challenge would have to wait until after his trial.

Al-Nashiri argued that military commissions only have authority over offenses that take place during an armed conflict. He said the U.S. was not officially at war with al-Qaida at the time of the attack.

Al-Nashiri’s trial date is not yet scheduled.