The US has announced charges against Khaled Sheikh Mohammed, the suspected mastermind of the 9/11 attacks on its territory, along with four other alleged plotters, vowing to seek the death penalty in the military trial.
The five suspects will face charges of terrorism, hijacking aircraft, conspiracy, murder in violation of the law of war and other counts.
"The charges allege that the five accused are responsible for the planning and execution of the attacks of September 11, 2001, in New York and Washington DC, and Shanksville, Pa, resulting in the killing of 2,976 people," the defence
department said in a statement.
"The convening authority referred the case to a capital military commission, meaning that, if convicted, the five accused could be sentenced to death."
Mohammed, along with Walid bin Attash and Mustafa al-Hawsawi of Saudi Arabia, Yemen's Ramzi bin al-Shibh, Pakistan's Ali Abd al-Aziz Ali - also known as Ammar al-Baluchi - will appear in court for arraignment proceedings within 30 days.
The trial, which could be months away, will be held at the US naval base in Guantanamo Bay, Cuba, where the US government has set up special military commissions to try terrorism suspects
The referral of charges comes one year after US President Barack Obama's administration abandoned efforts to try Mohammed and his four co-conspirators before a civilian court as the president had promised, and shifted the case to a military tribunal.
Attorney General Eric Holder blamed politicians for the policy reversal, saying their decision to block funding for prosecuting the September 11 suspects in a New York court had tied the administration's hands and forced it to move to a military trial.
The American Civil Liberties Union (ACLU) condemned the decision on Wednesday to proceed with a military trial.
"The Obama administration is making a terrible mistake by prosecuting the most important terrorism trials of our time in a second-tier system of justice," ACLU Executive Director Anthony Romero said in a statement.
"Whatever verdict comes out of the Guantanamo military commissions will be tainted by an unfair process and the
politics that wrongly pulled these cases from federal courts, which have safely and successfully handled hundreds of terrorism trials," he said.