The US president has approved the resumption of military trials for detainees at the Guantanamo Bay detention facility in Cuba.
The move ends a two-year ban and was the latest acknowledgement that the prison Barack Obama had vowed to shut down within a year of taking office will remain open for some time to come.
But even while announcing a resumption of military commission trials on Monday, Obama reaffirmed his support for trying terror suspects in US federal courts - something that has met resistance in Congress.
"I strongly believe that the American system of justice is a key part of our arsenal in the war against al-Qaeda and its affiliates, and we will continue to draw on all aspects of our justice system - including Article III courts - to ensure that our security and our values are strengthened,'' Obama said in a statement.
Article III courts are civilian tribunals.
USS Cole trial
Under Obama's order, defence secretary Robert Gates will rescind his January 2009 ban on bringing new cases against the terror suspects at the detention facility.
The first trial likely to proceed under Obama's new order would involve Abd al-Rahim al-Nashiri, the alleged mastermind of the 2000 bombing of the USS Cole. He has been imprisoned at Guantanamo since 2006.
Closure of the facility has become untenable because of questions about where terror suspects would be held.
Politicians have previously objected to their transfer to US federal courts, and Gates recently said that it has become
very difficult to release detainees to other countries because Congress has made that process more complicated.
Howard McKeon, chairman of the house armed services committee, said he was pleased with Obama's decision to restart the military commissions. But he said the administration must work with Congress to create a trial system that will stand up to judicial review.
A defence bill Obama had signed in January blocked the use of Defence Department dollars to transfer Guantanamo suspects to US soil for trial.
The White House said on Monday that it would work to overturn that prohibition.