Three of the men accused of plotting the 11 September 2001 attacks on the US have entered into a pre-trial agreement, the Department of Defense says.<br /><br />Khalid Sheikh Mohammed, Walid Muhammad Salih Mubarak Bin Attash, and Mustafa Ahmed Adam al-Hawsawi have been held at the US Navy base at Guantanamo Bay, Cuba, for years without going to trial.<br /><br />Details of the deal have not been announced, but US news outlets say the men will plead guilty in exchange for the prosecution agreeing not to seek the death penalty.<br /><br />Nearly 3,000 people in New York, Virginia and Pennsylvania were killed in the attacks, which sparked the "War on Terror" and the invasions of Afghanistan and Iraq.