People in Japan are calling Goto’s murder their 9/11. Photograph by Ahmed Muhammed Ali / Anadolu Agency / Getty

Why did ISIS execute a second Japanese hostage? Before the beheading of the journalist Kenji Goto, Japan didn’t think that it was even in a fight with the Islamic State. All Japan had done was contribute a couple of hundred million dollars in humanitarian aid to countries fighting ISIS. Then the man who has come to be known as Jihadi John, the executioner with the London accent seen in several of the group’s videos, threatened death to every Japanese person on the planet as he prepared to slaughter Goto. As a result, a political scientist at the University of Tokyo told the Times, “The cruelty of the Islamic State has made Japan see a harsh new reality. … We now realize we face the same dangers as other countries do.” People in Japan are now calling Kenji Goto’s murder their 9/11.

Why did ISIS allow its negotiations with Jordan to collapse? Jordan’s 9/11 occurred on November 9, 2005, when Iraqi suicide bombers blew up fifty-seven people in three Amman hotels, including twenty-seven members of a wedding party. One of the wedding-bombing team was a newly married woman named Sajida al-Rishawi, whose vest failed to detonate, and who is currently held in a Jordanian prison under a death sentence. The failure of the talks—a potential deal might have involved trading Goto and/or the Jordanian Air Force pilot Moaz al-Kasasbeh, an ISIS captive, for Rishawi—has apparently turned public opinion in Jordan, which is fertile ground for infiltration by the Islamic State, against ISIS. For its trouble the Islamic State got no cash and no Sajida al-Rishawi, only worldwide revulsion. (Update: The barbaric burning alive of Lieutenant al-Kasasbeh by ISIS makes no tactical sense. Nor does the release, Tuesday, of a video of his death. It will only enrage Jordanians. The Islamic State did it, the organization stated, to gladden the hearts of "believers"—as a morale booster.)

Meanwhile, the group is running out of high-profile hostages whom it can use to threaten, extort, and terrify the world. (The hundreds of Syrian journalists and activists who disappeared in ISIS territory, the hundreds or thousands of Yazidi women taken into sexual slavery, the tens or hundreds of thousands of ordinary Syrians and Iraqis living against their will under the Islamic State’s control—none of them, unfortunately, have much influence over international opinion.) So what’s the strategy behind the beheadings, other than to lengthen the list of countries that now talk about “their” 9/11? Why would ISIS want to make more enemies than it already has?

Why, for that matter, would ISIS send thousands of its men to besiege Kobani, a strategically unimportant Kurdish town on the Turkish-Syrian border where more than a thousand ISIS fighters, including many foreigners, perished after months of street fighting and American air raids? The Kurds, having secured a bitter victory, regard the destroyed city, with justified pride, as their Stalingrad. (Based on the pictures, the comparison does not seem like a stretch.) The world owes the people of Kobani a debt, and in the coming years the battle might be seen as a crucial milestone on the road to Kurdish nationhood. But why would ISIS throw away a large fraction of its fighting force there?

Is the larger aim to control all the lands in the Tigris and Euphrates river basin? If so, why do Islamic State spokesmen have a habit of declaring war against millions of citizens of various far-flung countries—Japan, France—on YouTube and Twitter?

It’s natural to ask these questions. We want to understand the Islamic State’s thinking, to anticipate its next moves, to assess its relative strength. But ISIS keeps on defying ordinary questions. The Islamic State doesn’t behave according to recognizable cost-benefit analyses. It doesn’t cut its losses or scale down its ambitions. The very name of the self-proclaimed caliphate strikes most people, not least other Muslims, as ridiculous, if not delusional. But it’s the vaulting ambition of an actual Islamic State that inspires ISIS recruits. The group uses surprise and shock to achieve goals that are more readily grasped by the apocalyptic imagination than by military or political theory. The capture of Mosul last June shocked the Iraqi and U.S. governments; for a while, ISIS seemed to believe that it could even take Baghdad. The genocidal attack on the Yazidis of Sinjar, in August, shocked the conscience. The videotaped beheadings that began at the same time shocked the West. Last week’s decapitation shocked Japan. Sooner or later, it seems, everyone will have a turn. And yet, if the group thinks that it will intimidate countries into keeping out of or leaving the anti-ISIS coalition, its tactics have so far been a failure.

In the end, it isn’t very useful to hold ISIS to the expectations and standards of other violent groups. Even Al Qaeda admonished Abu Musab al-Zarqawi, the founder of the Islamic State’s predecessor organization, Al Qaeda in Iraq, for his nasty habit of beheading hostages on camera. Why not a bullet to the back of the head, Ayman al-Zawahiri helpfully suggested from his hideout in the mountains along the Afghan-Pakistani border? But Zarqawi knew what he was doing, and he kept on, though he’s been vastly outperformed by his successors in ISIS. The point isn’t to use the right level of violence to achieve limited goals. The violence is the point, and the worse the better. The Islamic State doesn’t leave thousands of corpses in its wake as a means to an end. Slaughter is its goal—slaughter in the name of higher purification. Mass executions are proof of the Islamic State’s profound commitment to its vision.

There’s an undeniable attraction in this horror for a number of young people around the Middle East, North Africa, and even Europe and America, who want to leave behind the comfort and safety of normal life for the exaltation of the caliphate. The level of its violence hasn’t discouraged new recruits—the numbers keep growing, because extreme violence is part of what makes ISIS so compelling. Last year, Vice News shot a documentary in the Islamic State’s de facto capital of Raqqa, Syria, and what was striking in the footage was the happiness on the faces of ISIS followers. They revelled in the solidarity of a common cause undertaken at great personal risk. They are idealists—that’s what makes them so dangerous.

In this sense, ISIS is less like a conventional authoritarian or totalitarian state than like a mass death cult. Most such cults attract few followers and pose limited threats; the danger is mostly to themselves. But there are examples in modern history of whole societies falling under the influence and control of a mechanism whose aim is to dictate every aspect of life after an image of absolute virtue, and in doing so to produce a mountain of corpses. ISIS doesn’t behave like a regional insurgency or a global terrorist network, though it has elements of both. It joins the death cult to an army and a rudimentary state. It presents itself as the avant-garde of a mass movement, like the Khmer Rouge. The Islamic State resembles certain modern regimes driven by murderous ideologies, but it is also something new—as new as YouTube—and this makes it even harder to understand.

One thing we’ve learned from the history of such regimes is that they can be stronger and more enduring than rational analysis would predict. The other thing is that they rarely end in self-destruction. They usually have to be destroyed by others.