As the controversial new war film opens in Britain, a former Guantanamo guard tells Channel 4 News that he fears Zero Dark Thirty will encourage future young soldiers to "throw the rulebook out".

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Brandon Neely, who served as one of the first guards in Guantanamo in 2002, said the film's graphic depiction of torture methods risks legitimising such practises in the eyes of future soldiers.

Speaking to Channel 4 News from his home in Huntsville, Texas, he said: "There are enough people here who already support torture. I'm afraid this film is going to make people feel even more OK with it and think 'if this benefits us, let's just throw the rulebook out of the window'."

He is the latest to pour scorn on Kathryn Bigelow's (pictured, below) critically-acclaimed film that opened in Britain over the weekend. The three-hour epic, which tells the story of America's decade-long hunt for Osama bin Laden, is nominated for three Baftas but is at the centre of a growing dispute over how the filmmakers have chosen to depict the scenes of torture.

Mr Neely believes the controversy is symptomatic of a wider public apathy towards foreign policy as the US grapples with its domestic affairs, not least its economy. "People are only talking about torture now because of this film. That's it. If the film wasn't made, no one here would actually care. It is like our drones policy. Nobody talks about it," he says.

Kathryn Bigelow, director of Zero Dark Thirty (picture: Getty)

Torture techniques: the issue

Sleep deprivation, "waterboarding" and blasting loud music at prisoners under duress were among a catalogue of "enhanced interrogation techniques" allegedly used by some western guards and intelligence officers, particularly during the early years of George W Bush's administration.

Incidents such as Abu Ghraib and abuse of Baha Mousa, an Iraqi prisoner who died while imprisoned under British custody in September 2003 is where Mark Boale, the writer-producer of Zero Dark Thirty, has notably drawn many of his references.

But it is the film's central implication that it was torture-induced intelligence that paved the way the eventual discovery of Osama bin Laden which has sparked fury in the US. That version of events is vehemently refuted on Capitol Hill and has even prompted the CIA to make a rare public statement saying it is a "wrong impression".

Zero dark fury: when art and life cross

Dianne Feinstein and Carl Levin are among a growing number of angry senators who have written to Sony Pictures objecting to that version of events and sparking the possibility of a legal wrangle.

Last week a congressional investigation began into the extent of information that might have been shared between CIA officials and filmmakers. Meanwhile Senator John McCain, himself a torture victim during the Vietnam War, says the film made him "sick".

For now the filmmakers are standing firm. Ms Bigelow insists that "depicting" torture is not "endorsing it". "If it was, no artists would be able to paint inhumane practices, no author could write about them and no filmmaker could delve into the thorny subjects of our time,” she said last week, adding that torture was “part of the story we could not ignore".

A culture of secrecy or climate of apathy?

Neely was one of the first guards deployed in Guantanamo. He later served in Iraq before leaving the army to speak out against the treatment of prisoners he witnessed during his time as a prison guard.

Despite his protestations with the film's potential affects on young people, he draws clear parallels between Zero Dark Thirty and his own experiences. "When I was there, the interrogations had just started. All our manuals were related to prisoner of war camps: we were told that this was a detention facility and we would be writing the rules of it as we went along. We had no policies at all."

"The film shows detainees shackled up in a crucifix position. That happened in the early days. They would chain them up on the fence like that if they refused to take their medication and pretty much beat them in the way they did [in the film].

"The music torture, the short shackling, the excessive cold and heat with detainees as well as being slapped – a lot of my fellow guards have witnessed those things."

Mr Neely believes that the emotional burdens of those who partook and implement torture on the orders of others were stories that would "probably never be told".

Kunal Dutta is a news writer and reporter based in London.