Five men accused of plotting the 11 September 2001 attacks on the US, including alleged mastermind Khalid Sheikh Mohammed, will be tried in a civilian court in New York.
The five were being prosecuted in US military commissions at Guantanamo Bay, but the Obama administration has pledged to close the controversial prison and move some of the cases to traditional US criminal courts for trial.
Some detainees will still be tried in military tribunals, including the accused mastermind of the 2000 attack on the USS Cole warship in Yemen, Abd al-Rahim al Nashiri.
The move marks one of the first major steps by the Obama administration to close the prison, which he has pledged to do by 22 January 2010.
However, Barack Obama and his team have faced numerous political and diplomatic hurdles and some officials admit it may be hard to meet the deadline.
There are 215 detainees at the Guantanamo detention camp which was set up in early 2002 by the Bush administration to house terrorism suspects.
Trials in New York may provoke strong public reactions, particularly since it was the site of the 2001 attacks that destroyed the World Trade Centre's twin towers and killed nearly 3,000 people.
One Guantanamo detainee, Ahmed Khalfan Ghailani, has already been sent from Guantanamo to New York to be tried on charges of being involved in the 1998 bombings of US embassies in Tanzania and Kenya that killed 224 people.
The four other 9/11 suspects being held at Guantanamo are Walid bin Attash, Ramzi Binalshibh, Ali Abdul Aziz Ali and Mustafa Ahmed al Hawsawi.
It is not clear where the suspects will be held while they are awaiting trial but some have suggested the US Naval Consolidated Brig in South Carolina.
