Are we still talking about the banality of evil? When that overworked phrase was first used by philosopher Hannah Arendt, it described the blank persona of Nazi war criminal Adolf Eichmann. Now, in NAZA, anonymised members of Israeli intelligence discuss their remote execution of the assault on Gaza. The comparison to Hitler’s Germany, while understandably controversial, is made by a subject themselves. If they are banal, it is a modern, oddly familiar kind. These are articulate, middle-class millennials. They say they are leftwing and non-racist. Put differently, they could be Guardian readers.

And yes, one remarks, they have been conducting a genocide.

The work of directors Yuval Abraham and Rachel Szor is shattering. But we have been shattered before by the firsthand accounts of people who carry out atrocities – sometimes called perpetrator cinema. In 2013, director Joshua Oppenheimer released The Act of Killing, an astonishing film involving members of 1960s right-wing Indonesian death squads. It was lavishly acclaimed. Since then, it has only kept feeling painfully relevant.

Before that, documentary wild card Errol Morris made Standard Operating Procedure, interviewing US soldiers who abused Iraqis at the notorious Abu Ghraib jail. Edging into drama, you might even include Jonathan Glazer’s The Zone of Interest, where the commandant of Auschwitz lives happily with his wife and children. (Glazer is an executive producer of NAZA, which is produced by the Guardian.)

Questions gnaw through them all. To begin: who is it that commits crimes against humanity? The answer can feel inconclusive. NAZA is filled with Tel Aviv high-fliers, some citing as justification the horrific attacks of October 7. But the American troops of Standard Operating Procedure are ordinary grunts in the “war on terror”. Meanwhile, in The Act of Killing, ageing street thugs recreate their murders of trade unionists and teachers as the action movies they imagine them being. Flamboyance blooms in the abyss.

In every case, what we see won’t leave our heads, even as we flail for an adequate response. The late critic Roger Ebert famously called movies “empathy machines”. But these films short circuit the machinery. How can we empathise with people who seem to show no remorse?

For some, NAZA presents a bigger problem than that. The Israeli government has floated stripping Abraham and Szor of their citizenship, among other threats. But even for audiences far from the Middle East, the film is hard to deal with. We may feel anguished just as we are reminded how safe our anguish is. We might even think about that most unfriendly word: complicity.

But perpetrator cinema is about more than complicity. It is about the attempt to fathom the perpetrator. Discussing NAZA on the Jewish Currents podcast, Oppenheimer spoke to that task. “To understand a crime as a human activity, we have to look at the human beings who undertake that activity.”

Or do we understand mass murderers enough through what they do? In 2013, The Act of Killing also met pungent criticism. One influential figure in British documentary publicly called it a “snuff film”. (Oppenheimer next made The Look of Silence, about the victims.) And NAZA has faced pre-emptive criticism from Palestinians, including poet Mosab Abu Toha, arguing that the last three years in Gaza have already been documented by Gazans. “It’s all there,” he posted on social media. “So what will this film add?”

In this reading, NAZA is accused of privileging the perpetrator – giving literal voice to those for who the best platform, perhaps, would be a trial at the Hague. And yet another question is both obvious and uncomfortable. What’s in it for them anyway?

In this year’s documentary Killing Anna, former Syrian army officers were catfished into discussing civilian massacres by an academic posing as a loyalist of Bashar al-Assad. But most perpetrators are wholly aware they are being recorded. As such, we might expect a sobbing confessional. Not quite.

The torturers of Standard Operating Procedure came close now and then, but only amid a lot of evasion. As further ethical complication, they were also paid for their interviews. With The Act of Killing, though, Oppenheimer found a still more disturbing truth – his butchers were gleefully unrepentant. (They also believed that, as an American, he would approve of garrotting leftists.) And in NAZA, Yuval Abraham has said some of his interviewees spoke from “the opposite of shame”. That word complicity comes up again. Should a film-maker be doing this?

The thing is, though, lack of shame has a price. “War crimes are defined by the winners,” an Indonesian gangster says in The Act of Killing. “I’m a winner, so I can make my own definition.” In these films, that definition changes hands. Brilliantly, Oppenheimer did it by granting his subjects the freedom to reveal their nightmare psyches. In NAZA, journalism of the highest quality draws out a guilty plea with a seemingly howling lack of conscience.

Palestinian accounts of the assault on Gaza have been wrongly ignored. The response, to this Israeli version, of the Netanyahu government is telling. Aside from menacing the directors, a mimicking rebuttal, Naza: The Real Story was recently launched, desperately trying to reclaim control of the story.

And a director’s “complicity” is often indispensable. In 2017, the scalding Adriana’s Pact saw Chilean documentary maker Lissette Orozco interview her aunt, rumoured to have worked for the secret police of dictator Augusto Pinochet. When it turned out she had, the aunt’s berserk response to what she saw as a family betrayal was crucial to the story. Now the exposures of NAZA come from interviewees who would presumably never have talked to Abraham and Szor were they not Israeli too.

But more than that – the fact they are is also proof that Israelis can still say no to this Israel. Vital as they are elsewhere, the real power of these films is in the societies they portray. Official Indonesian history echoed the gangsters’ tales of bravely ridding the country of communists. Oppenheimer made the film available free there. Now NAZA confronts the belief that atrocities are only ever down to far-right “bad apples”. In perpetrator cinema, a common thread is directing us to unseen hierarchies – the politicians and generals whose lies to their own people are now laid bare.

Put like that, hope almost glimmers. Still. These films advise caution. Hollywood movies are delivery systems for catharsis. Here, it is elusive. Near the end of The Act of Killing, the most naggingly sympathetic of the subjects starts to retch, as if his body is trying to expel his own past. But nothing comes up. And now we watch NAZA, and know what has happened in Gaza still happens today.

No, what hope perpetrator cinema gives us is specific. Appearing with Oppenheimer on the Jewish Currents pod, Palestinian film-maker Rami Younis recalled meeting a giant of his country’s cinema, director Hany Abu-Assad, whose movies had been accused of humanising Israeli police. “What do you think happens when you keep demonising your enemy?” Abu-Assad said. “What happens to you?”

Usually “humanising” implies a soft focus. But NAZA and The Act of Killing remind us being human involves being capable of evil. They also offer the chance to fight back. The perpetrator of genocide refuses to see their enemy as like themselves – to truly look at them. With perpetrator cinema, though, we can look hard at people with whom we would like to share nothing – and say we are both human, however monstrous that also makes us.

• NAZA is in cinemas worldwide and will screen on the Guardian’s website from late November