The Gatekeepers: A Zero Dark Thirty, with added morals

Long before its December release in his native Israel, Dror Moreh's documentary The Gatekeepers was one of the most hotly debated movies in years. "The number of articles about the film was unprecedented", says Moreh. Given the incendiary nature of his film, he can hardly have been surprised by the reaction. Interviewing all six living former heads of Israel's Shin Bet counterterrorism agency, The Gatekeepers is a startling study of how Israeli state-sanctioned violence has derailed the peace process. Fuelled by remarkably frank confessions from these expert tacticians, not least regarding their involvement in selective terrorist assassinations, it makes for grim, if compelling, viewing.

Even more impressive has been the film's American performance. After wowing critics at the Toronto and Sundance festivals, the film has taken $1.6m; recently expanding on to 80 screens, it's a remarkable run for a niche documentary about Israeli politics. As for the school of thought that Americans don't go to see subtitled films, "The Gatekeepers proved that wrong," notes Moreh.

Suddenly regarded as a Hollywood hot prospect, the only surprise was that Moreh, 51, lost out on the Best Documentary Oscar (to the less controversial Searching for Sugar Man). He can't help but smile when he reflects on that night. "It was amazing. Just the fact that you meet all your idols. Steven Spielberg, Kathleen Kennedy, Ben Affleck… all of them saw the film. It speaks about dilemmas that America deals with now, very vigorously – targeted assassination, drone attacks, torturing people in order to get intel, the war of the 21st century – how is it working, is it not working? And who can speak about it more than the heads of the Israeli secret service?"

He even met Kathryn Bigelow and Mark Boal, the director and writer of Zero Dark Thirty. "Kathryn Bigelow said, 'I was blown away completely by your movie. Completely.'" For his part Moreh remains critical of their work. "Zero Dark Thirty doesn't touch issues about morality. It's almost a journalistic, documentary description of what happened. Does it ask itself the question about the morality of water-boarding people? If Mark Boal had taken morality into consideration it would've created a different kind of potency."

The Gatekeepers is unflinching in its examination of the morality of counterterrorism – not least when Moreh confronts Avraham Shalom. The much-feared head of Shin Bet from 1980-86, he became infamous after he ordered the execution of two terrorists captured after hijacking a bus between Tel Aviv and Ashkelon. "With terrorists there are no morals," he says, in the face of Moreh's questioning. "In the war against terror, forget about morality."

Raised in Jerusalem – his mother is from Palestine, his father originally from Iraq – Moreh was "shocked" to learn how many missed opportunities there were by Israelis to broker peace. "The actual meaning of that is that people die. Many Israelis and Palestinians could've lived happily. Lives have been lost and life will be lost... because the politicians from both sides didn't work hard enough to reach a solution."

Moreh is now returning to Tel Aviv to complete a book and a five-part television series that will expand on the The Gatekeepers. And he has his eye on Hollywood. "I got a lot of offers to work on a fiction film," he says. Would he consider using one of the anecdotes from the documentary as the basis for a script? "I will do something exactly like that," he says. He cites one of the more pulsating sequences in the film – an account of an 18-month Shin Bet operation to bring down the chief bombmaker of Hamas, Yahya Ayyash. Known as the Engineer, he was killed in 1996 by a mobile phone rigged with explosives. "Believe me, I can do a Steven Spielberg movie about that case," he says.

'The Gatekeepers' opens on Friday