The Pentagon will appeal a military judge’s ruling that plea agreements struck to avoid the death penalty for Khalid Sheikh Mohammed, the alleged mastermind of the 11 September 2001 terrorist attacks on the US, and two of his co-defendants are valid, a defense official said on Saturday. The ruling voids defense secretary Lloyd Austin’s order to revoke the deals and concluded that the plea agreements were valid. The judge granted the three motions to enter guilty pleas and said he would schedule them for a future date to be determined by the military commission. The plea agreements would spare Mohammed, Walid bin Attash and Mustafa al-Hawsawi the risk of the death penalty in exchange for guilty pleas in the long-running 9/11 case and would be a key step toward closing out prosecutions related to the attacks by al-Qaida that killed nearly 3,000 people in the US. The defense department will also seek a postponement of any hearing on the pleas, according to the official, who was not authorized to publicly discuss legal matters and spoke on condition of anonymity. R Adm Aaron Rugh, the chief prosecutor, sent a letter on Friday to the families of 9/11 victims informing them of the decision. The ruling by the judge, Col Matthew McCall of the air force, allowed the three 9/11 defendants to enter guilty pleas in the US military courtroom at Guantánamo Bay, the US base in Cuba. Government prosecutors had negotiated the deals with defense lawyers under government auspices, and the top official for the military commission at Guantánamo had approved the agreements. But the deals were immediately criticized by Republican lawmakers and others when they were made public this summer. Families of 9/11 victims said the plea deals destroyed any chance of a full trial that could have ended in death sentences and given people the opportunity to address the men accused of killing their loved ones. “I would have liked a trial of men who hadn’t been tortured, but we got handed a really poor opportunity for justice, and this is a way to verdicts and finality,” Terry Kay Rockefeller, 74, whose sister Laura was killed on 9/11, told the Washington Post. Within days, Austin had issued an order saying he was nullifying the plea bargains, but the judge had ruled that Austin lacked the legal authority to toss them.