Obama signs defence bill making Guantanamo closure tougher

Away from public view, US President Barack Obama on Wednesday signed a $607bn defence bill 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 Authorisation Act 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 bill upholds a ban on transferring prisoners from Gitmo to the US. Obama had vetoed an earlier version of the bill that included restrictions on closing the prison camp.

In a written statement on Wednesday, 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 some prisoners to a specialised facility in the US is at the heart of the White House strategy to close Guantanamo.

Obama came to office in 2009 vowing to shutter the facility that flashed images of caged men in orange jumpsuits being subjected to "enhanced interrogation" - viewed by human rights groups as torture - around the world.

"Maintaining this site, year after year, is not consistent with our interests as a nation and undermines our standing in the world, Obama said in a statement.

“The executive branch must have the flexibility, with regard to the detainees who remain at Guantanamo, to determine when and where to prosecute them, based on the facts and circumstances of each case and our national security interests, and when and where to transfer them consistent with our national security and our humane treatment policy,” Obama wrote.

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 in 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.