All six of THE GATEKEEPERS (Avner Shahaf/Irit Harel/Sony Pictures Classics)

The Gatekeepers thoughtfully examines the difficulties of protecting a democracy from internal enemies. While Americans are more familiar from movies and TV with Israel’s Mossad, which handles international threats, the Shin Bet is that country’s domestic intelligence agency. Director Dror Moreh’s interviews with its living leaders provide a revealing look at Israel’s recent history, with sobering recommendations for a negotiated future, based on hard-earned experiences.

Moreh was inspired by Errol Morris’s The Fog of War (2004), but that film’s sole interviewee, former U.S. Defense Secretary Robert McNamara, had been a visible, public figure whose opinions about leading the Vietnam War were well-known, making his on-camera reinterpretation of the conflict startling. In the same style, Moreh interviews six former heads of the agency, whose motto is “Defender that shall not be seen.” The public may presume their hard-line views toward Palestinian and Jewish perils, but their realpolitik towards peace had previously only been told to one journalist.

Moreh effectively borrows some of Morris’s techniques, letting these heretofore secretive men provide biographical context for how they view the world, interviewing them in their own homes, and illustrating their narratives with news clips and recreated scenes in (ghostly-looking) CGI, as if their headquarters and crises were spied on through closed circuit TV. Soberly pithy quotes—like “One man’s terrorist is another man’s freedom fighter”—are pulled out as chapter headings.

Though the documentary starts after the Camp David peace treaty with Egypt, Avraham Shalom (Shin Bet head from 1980–1986, serving under three prime ministers) is the oldest, and the easiest to distinguish from the others throughout. He had a tough military career going back before independence. (The director says his childhood reminisces of Nazis in his native Vienna had to be left out. Perhaps they will be a DVD extra.) So it’s that’s much more moving to see him, for the first time, talk about what brought his career to an end, a 1984 terrorist attack on a bus outside of Tel Aviv that Americans may not be familiar with, let alone aware of the ramifications of the consequent scandal, when two surviving terrorists were killed under illegal circumstances.

His bitterness establishes a theme for the rest of the film. He pretty much says he took the fall for what elected leaders approved for him to do: “They abandoned the wounded on the field—us, the Shin Bet. That’s why I don’t take the politicians seriously anymore.” What is surprising in the film’s repeated criticism of government leaders is that it is not directed at civilian armchair generals, but at cabinets led by real ex-generals who were revered war heroes. (Moreh’s previous documentary was Sharon (2008), which will have a belated U.S. theatrical release next month.)

One ex-chief has even become a politician. Yaakov Peri (serving 1988-1995 during the First Intifada) wryly notes: “When you retire, you become a bit of a leftist.” He was just elected to the Knesset in the new centrist Yesh Atid party that had surprising success in the latest elections. The most recent director, Yuval Diskin (from 2005-2011), wearily agrees with a quote from a leftist Israeli about the insidious negative influence on Israel of the West Bank occupation.

The 1995 assassination of Prime Minister Yitzhak Rabin by a Jewish extremist happened during the brief leadership of Carmi Gillon, and each man talks movingly of how that horror shook him up. One says the rise of such right-wing threats were no secret, but again, politicians are blamed, with the mention that the ultra-religious are represented in the Knesset and have over the years been partners in governing coalitions. Also blamed is the free speech protection of rabble-rousing rabbis. The agency belatedly ratcheted up intelligence operations against extremists, and had successes in stopping some homegrown attacks.

During his term from 2000-2005, Avi Dichter helped initiate the notorious Separation Wall penning the Palestinians in the Occupied Territories as part of his aggressively successful efforts to decrease suicide bombings, but Moreh barely discusses that. Dichter’s 1996-2000 predecessor, Ami Ayalon is the only one who was raised on a kibbutz, and he talks sadly about losing his idealism, even though he is the one who has become a peace activist.

In drawing out these professional interrogators, Moreh is much less accusatory than Ra’anan Alexandrowicz in his interviews with military lawyers in last year’s The Law in These Parts, about the military administration of the occupation. But his focus on their concurrence over the need for a two-state negotiation has probably helped this film win international accolades, including an Oscar nomination for best documentary.