Three Sept. 11 suspects agree to plead guilty at Guantanamo

The man accused of masterminding the Sept. 11 attacks, Khalid Sheikh Mohammed, and two of his accomplices, held at the U.S. military prison at Guantanamo Bay, Cuba, have agreed to plead guilty, the Pentagon said on Wednesday.

Mohammed is accused of masterminding the plot to fly hijacked commercial passenger aircraft into the World Trade Center in New York City and into the Pentagon. The 9/11 attacks, as they're known, killed nearly 3,000 people and plunged the United States into what would become a two-decade-long war in Afghanistan.

His interrogations have long been the subject of scrutiny. A 2014 Senate Intelligence Committee report on the CIA's use of waterboarding and other "enhanced interrogation techniques" said that Mohammed had been waterboarded at least 183 times.

Plea deals were also reached by two other detainees: Walid Muhammad Salih Mubarak Bin 'Attash and Mustafa Ahmed Adam al Hawsawi, according to a Pentagon statement.

The three men were initially charged jointly and arraigned on June 5, 2008, and then were again charged jointly and arraigned a second time on May 5, 2012, the Pentagon statement said.