A US federal appeals court has annulled a plea deal for Khalid Sheikh Mohammed, the alleged mastermind of the 9/11 attacks, which would have spared him from capital punishment. The decision prolongs the military prosecution process that has faced numerous challenges over the past two decades. The deal, negotiated over two years, was intended to provide life sentences without parole for Mohammed and co-defendants, but faced mixed reactions from victims' families. The court ruled that then-Defense Secretary Lloyd Austin acted within his authority to reject the deal.