Khalid Sheikh Mohammed, accused of being the mastermind behind the 9/11 attacks in the US, has agreed to plead guilty, according to the Defense Department. This comes nearly twenty-three years after the terror group Al-Qaeda carried out the deadliest terror attack in the history of the United States and the world. Mohammed, along with accomplices Walid bin Attash and Mustafa al-Hawsawi, are expected to enter their guilty pleas at the military commission at Guantanamo Bay, Cuba, as soon as next week. The development could bring a long-delayed resolution to the attack that claimed thousands of l…