The continued existence of the camp has been a thorn in the side of President Barack Obama who promised to close the camp while campaigning for president, but was thwarted by Republicans in Congress who blocked the transfer of detainees to the mainland.
The facility was opened in January 2002 as a site to hold and interrogate terrorism suspects, including those involved in planning the September 11 attacks, but swiftly became infamous for its treatment of inmates.
A total of 116 detainees are currently held at Guantanamo, of which 64 are considered too dangerous to be released. The other 52 have already been recommended for transfer, but arrangements must be reached with countries willing to accept the inmates on their soil.
Among the detainees still in legal limbo on the island is Shaker Aamer, a Saudi-born British citizen who has twice been cleared for release, by the Bush Administration in 2007, and by Obama in 2009.
Aamer's continued detention is a source of embarrassment for British authorities who have made repeated representations for the 46-year-old to be freed.
Obama's top advisers have reportedly been debating the best approach to closing the facility in Obama's final 18 months as president behind the scenes.
Hurdles to closing the camp
• National Security
Closing the camp requires safely relocating its 116 detainees. Previous relocations have seen fighters returning to the battlefield and the US would want to avoid a former inmate attacking the mainland.
• US Congress
The Republican-controlled US Congress has blocked any federal funding to transfer detainees to the US mainland where they could be held in a maximum security prison and put on trial. A vote on the issue last year fell along party lines.
• Legal issues
Many detainees face vague conspiracy charges based on hearsay evidence that would probably be inadmissible in a US federal court. Holding detainees in open-ended detention on the US mainland is opposed by human rights groups.
• Public opinion
Following the rise of Isis and the beheading of Western hostages in Syria and Iraq this year, sympathy for the plight of detainees has lessened, increasing political risk for Obama of a release going wrong.
• International help
The Administration needs more countries prepared to take detainees who are willing to guarantee both their security and that the won't be tortured by governments with poor records on the use of torture.