Dror Morah’s extraordinary documentary sketches the history of the Israeli-Palestinian conflict from the perspective of the directors of Shin Bet, the Israeli counterterrorism unit. “The Gatekeepers” are the six interviewees who headed the agency at various points over the past three decades, and they speak with remarkable candor, a good deal of pride over what they accomplished but also no little regret about what they failed to prevent. What becomes clear is that the experience of all the men had the effect of bringing them, to greater or lesser extent, to a profound disquiet about how Israeli policy has developed over the years and a low opinion of most of the political leaders they served.

Archival footage lays out in brief the first decade of Israel’s national life, but it’s really with the Six-Day War of 1967 and the occupation of Palestinian territory that followed it that the first-person narrative really begins. Avraham Shalom, who headed Shin Bet between 1980 and 1986 and the oldest of the interviewees, recalls how the use of military force to secure tranquility led instead to a cycle of violence, attack and counterattack, that has grown increasingly vicious over time and made it virtually impossible to find common ground that might finally bring peace to the region. The possibility of cooperation between Israeli and Palestinian intelligence agencies—which once was quite vibrant—collapsed over time, and the emergence of groups like Hezbollah in Lebanon and Hamas in the Gaza Strip was a result.

But though Shalom expresses doubts about the wisdom of the policies toward the Palestinians developed after 1967, he remains a hard-liner in terms of the application of strong measures when they’re necessary, and he remains closed-lipped about his own involvement in a case in which Palestinian bus highjackers who’d been taken captive were killed by soldiers. Another interviewee speak enthusiastically of expertly targeted assassinations—like that of a Hamas bomb-maker who was killed with an explosive cell phone in a carefully-planned operation (though one that initially didn’t come off as planned). And one regrets the failure to approve an airstrike that might have wiped out the leadership of Hamas in a single stroke because of fear of collateral damage and civilian deaths.

There’s pain in all of this, but also poignancy in the remembrance of Prime Minister Yitzhak Rabin, whose decision to reach out to the Palestinians led to his assassination by a Jewish rightist, which all the interviewees agree, fundamentally changed Israeli attitudes and began the strong turn in Israeli opinion toward the harsher, far less accommodating policies characteristic of the current government. One message that comes through loud and clear is that even as Shin Bet became ever more effective in its anti-terrorist activities, the heads of the agency recognized that Israel’s overall security nonetheless declined—leading one of them to remark that as you grow older in the practice of his profession, it’s pretty much inevitable that you’ll love to the left.

Intelligently put together, with archival footage, graphics and some recreations skillfully employed to fill out the story and tie the various interview threads together smoothly, “The Gatekeepers” is not only an engrossing first-hand account of Israel’s Palestinian policies over time, but one that may have lessons to teach both Israeli leaders and other nations confronting those they identify as terrorists.