Washington (AFP) - Away from public view, US President Barack Obama signed a defense bill Wednesday barbed with measures designed to undo his bid to close the prison at Guantanamo Bay.
In a terse statement, the White House said Obama has signed the National Defense Authorization Act (NDAA) for Fiscal Year 2016, along with several other pieces of legislation.
Obama's signature significantly lengthens the odds that he will be able to close Guantanamo before leaving office in early 2017.
The $615 billion defense policy bill upholds a ban on transferring prisoners to the United States from the US naval base at Guantanamo Bay, Cuba.
In a separate written statement, Obama said he was "deeply disappointed that the Congress has again failed to take productive action toward closing the detention facility at Guantanamo."
He warned that his administration views some of the curbs on prisoner transfers as potentially unconstitutional.
Along with transfers to foreign countries, moving the most dangerous prisoners to a specialized facility in the United States is at the heart of the White House strategy to close Guantanamo.
Obama came to office in 2009 vowing to shutter the facility, which opened under his predecessor George W. Bush to hold terror suspects after the September 11, 2001 attacks and became notorious for harsh interrogation techniques.
"Maintaining this site, year after year, is not consistent with our interests as a nation and undermines our standing in the world," Obama said.
Obama has seen his efforts repeatedly thwarted by Congress.
In the latest setback, the White House has asked the Pentagon to look again at a master plan to close the facility.
Whenever those measures are published, they are sure to face resistance from the Republican-controlled Congress.
But Obama has so far been unwilling to commit to closing the facility by executive order, a move that would likely spark a political firestorm and multiple lawsuits.
"It is long past time for the Congress to lift the restrictions it has imposed and to work with my administration to responsibly and safely close the facility, bringing this chapter of our history to a close," Obama said.
The NDAA also notably includes a ban on torture during interrogations, a measure aimed at ending brutal techniques that were used on terror suspects following 9/11.
The provision was co-authored by Republican Senator John McCain, who was tortured in Vietnam where he was a prisoner of war.
"Enactment of this legislation ensures the United States will never again violate its laws or moral code by using torture," said Senator Dianne Feinstein, the Intelligence Committee's top Democrat who wrote the provision with McCain.
Feinstein said the CIA's use of torture after 9/11 was used as a recruitment tool by terrorists.
"We must learn from our mistakes so we don't repeat them," she added.