IV. The Fight

The ideological purity of the Islamic State has one compensating virtue: it allows us to predict some of the group's actions. Osama bin Laden was seldom predictable. He ended his first television interview cryptically. CNN's Peter Arnett asked him, "What are your future plans?" Bin Laden replied, "You'll see them and hear about them in the media, God willing." By contrast, the Islamic State boasts openly about its plans—not all of them, but enough so that by listening carefully, we can deduce how it intends to govern and expand.

In London, Choudary and his students provided detailed descriptions of how the Islamic State must conduct its foreign policy, now that it is a caliphate. It has already taken up what Islamic law refers to as "offensive jihad," the forcible expansion into countries that are ruled by non-Muslims. "Hitherto, we were just defending ourselves," Choudary said; without a caliphate, offensive jihad is an inapplicable concept. But the waging of war to expand the caliphate is an essential duty of the caliph.

Choudary took pains to present the laws of war under which the Islamic State operates as policies of mercy rather than of brutality. He told me the state has an obligation to terrorize its enemies—a holy order to scare the shit out of them with beheadings and crucifixions and enslavement of women and children, because doing so hastens victory and avoids prolonged conflict.

Choudary's colleague Abu Baraa explained that Islamic law permits only temporary peace treaties, lasting no longer than a decade. Similarly, accepting any border is anathema, as stated by the Prophet and echoed in the Islamic State's propaganda videos. If the caliph consents to a longer-term peace or permanent border, he will be in error. Temporary peace treaties are renewable, but may not be applied to all enemies at once: the caliph must wage jihad at least once a year. He may not rest, or he will fall into a state of sin.

One comparison to the Islamic State is the Khmer Rouge, which killed about a third of the population of Cambodia. But the Khmer Rouge occupied Cambodia's seat at the United Nations. "This is not permitted," Abu Baraa said. "To send an ambassador to the UN is to recognize an authority other than God's." This form of diplomacy is shirk, or polytheism, he argued, and would be immediate cause to hereticize and replace Baghdadi. Even to hasten the arrival of a caliphate by democratic means—for example by voting for political candidates who favor a caliphate—is shirk.

It's hard to overstate how hamstrung the Islamic State will be by its radicalism. The modern international system, born of the 1648 Peace of Westphalia, relies on each state's willingness to recognize borders, however grudgingly. For the Islamic State, that recognition is ideological suicide. Other Islamist groups, such as the Muslim Brotherhood and Hamas, have succumbed to the blandishments of democracy and the potential for an invitation to the community of nations, complete with a UN seat. Negotiation and accommodation have worked, at times, for the Taliban as well. (Under Taliban rule, Afghanistan exchanged ambassadors with Saudi Arabia, Pakistan, and the United Arab Emirates, an act that invalidated the Taliban's authority in the Islamic State's eyes.) To the Islamic State these are not options, but acts of apostasy.

The United States and its allies have reacted to the Islamic State belatedly and in an apparent daze. The group's ambitions and rough strategic blueprints were evident in its pronouncements and in social-media chatter as far back as 2011, when it was just one of many terrorist groups in Syria and Iraq and hadn't yet committed mass atrocities. Adnani, the spokesman, told followers then that the group's ambition was to "restore the Islamic caliphate," and he evoked the apocalypse, saying, "There are but a few days left." Baghdadi had already styled himself "commander of the faithful," a title ordinarily reserved for caliphs, in 2011. In April 2013, Adnani declared the movement "ready to redraw the world upon the Prophetic methodology of the caliphate." In August 2013, he said, "Our goal is to establish an Islamic state that doesn't recognize borders, on the Prophetic methodology." By then, the group had taken Raqqa, a Syrian provincial capital of perhaps 500,000 people, and was drawing in substantial numbers of foreign fighters who'd heard its message.

If we had identified the Islamic State's intentions early, and realized that the vacuum in Syria and Iraq would give it ample space to carry them out, we might, at a minimum, have pushed Iraq to harden its border with Syria and preemptively make deals with its Sunnis. That would at least have avoided the electrifying propaganda effect created by the declaration of a caliphate just after the conquest of Iraq's third-largest city. Yet, just over a year ago, Obama told The New Yorker that he considered ISIS to be al-Qaeda's weaker partner. "If a jayvee team puts on Lakers uniforms that doesn't make them Kobe Bryant," the president said.

Our failure to appreciate the split between the Islamic State and al-Qaeda, and the essential differences between the two, has led to dangerous decisions. Last fall, to take one example, the U.S. government consented to a desperate plan to save Peter Kassig's life. The plan facilitated—indeed, required—the interaction of some of the founding figures of the Islamic State and al-Qaeda, and could hardly have looked more hastily improvised.

It entailed the enlistment of Abu Muhammad al Maqdisi, the Zarqawi mentor and al-Qaeda grandee, to approach Turki al-Binali, the Islamic State's chief ideologue and a former student of Maqdisi's, even though the two men had fallen out due to Maqdisi's criticism of the Islamic State. Maqdisi had already called for the state to extend mercy to Alan Henning, the British cabbie who had entered Syria to deliver aid to children. In December, The Guardian reported that the U.S. government, through an intermediary, had asked Maqdisi to intercede with the Islamic State on Kassig's behalf.

Maqdisi was living freely in Jordan, but had been banned from communicating with terrorists abroad, and was being monitored closely. After Jordan granted the United States permission to reintroduce Maqdisi to Binali, Maqdisi bought a phone with American money and was allowed to correspond merrily with his former student for a few days, before the Jordanian government stopped the chats and used them as a pretext to jail Maqdisi. Kassig's severed head appeared in the Dabiq video a few days later.

Maqdisi gets mocked roundly on Twitter by the Islamic State's fans, and al‑Qaeda is held in great contempt for refusing to acknowledge the caliphate. Cole Bunzel, a scholar who studies Islamic State ideology, read Maqdisi's opinion on Henning's status and thought it would hasten his and other captives' death. "If I were held captive by the Islamic State and Maqdisi said I shouldn't be killed," he told me, "I'd kiss my ass goodbye."

Kassig's death was a tragedy, but the plan's success would have been a bigger one. A reconciliation between Maqdisi and Binali would have begun to heal the main rift between the world's two largest jihadist organizations. It's possible that the government wanted only to draw out Binali for intelligence purposes or assassination. (Multiple attempts to elicit comment from the FBI were unsuccessful.) Regardless, the decision to play matchmaker for America's two main terrorist antagonists reveals astonishingly poor judgment.

Chastened by our earlier indifference, we are now meeting the Islamic State via Kurdish and Iraqi proxy on the battlefield, and with regular air assaults. Those strategies haven't dislodged the Islamic State from any of its major territorial possessions, although they've kept it from directly assaulting Baghdad and Erbil and slaughtering Shia and Kurds there.

Some observers have called for escalation, including several predictable voices from the interventionist right (Max Boot, Frederick Kagan), who have urged the deployment of tens of thousands of American soldiers. These calls should not be dismissed too quickly: an avowedly genocidal organization is on its potential victims' front lawn, and it is committing daily atrocities in the territory it already controls.

One way to un-cast the Islamic State's spell over its adherents would be to overpower it militarily and occupy the parts of Syria and Iraq now under caliphate rule. Al‑Qaeda is ineradicable because it can survive, cockroach-like, by going underground. The Islamic State cannot. If it loses its grip on its territory in Syria and Iraq, it will cease to be a caliphate. Caliphates cannot exist as underground movements, because territorial authority is a requirement: take away its command of territory, and all those oaths of allegiance are no longer binding. Former pledges could of course continue to attack the West and behead their enemies, as freelancers. But the propaganda value of the caliphate would disappear, and with it the supposed religious duty to immigrate and serve it. If the United States were to invade, the Islamic State's obsession with battle at Dabiq suggests that it might send vast resources there, as if in a conventional battle. If the state musters at Dabiq in full force, only to be routed, it might never recover.

Abu Baraa, who maintains a YouTube channel about Islamic law, says the caliph, Baghdadi, cannot negotiate or recognize borders, and must continually make war, or he will remove himself from Islam.

And yet the risks of escalation are enormous. The biggest proponent of an American invasion is the Islamic State itself. The provocative videos, in which a black-hooded executioner addresses President Obama by name, are clearly made to draw America into the fight. An invasion would be a huge propaganda victory for jihadists worldwide: irrespective of whether they have given baya'a to the caliph, they all believe that the United States wants to embark on a modern-day Crusade and kill Muslims. Yet another invasion and occupation would confirm that suspicion, and bolster recruitment. Add the incompetence of our previous efforts as occupiers, and we have reason for reluctance. The rise of ISIS, after all, happened only because our previous occupation created space for Zarqawi and his followers. Who knows the consequences of another botched job?

Given everything we know about the Islamic State, continuing to slowly bleed it, through air strikes and proxy warfare, appears the best of bad military options. Neither the Kurds nor the Shia will ever subdue and control the whole Sunni heartland of Syria and Iraq—they are hated there, and have no appetite for such an adventure anyway. But they can keep the Islamic State from fulfilling its duty to expand. And with every month that it fails to expand, it resembles less the conquering state of the Prophet Muhammad than yet another Middle Eastern government failing to bring prosperity to its people.

The humanitarian cost of the Islamic State's existence is high. But its threat to the United States is smaller than its all too frequent conflation with al-Qaeda would suggest. Al-Qaeda's core is rare among jihadist groups for its focus on the "far enemy" (the West); most jihadist groups' main concerns lie closer to home. That's especially true of the Islamic State, precisely because of its ideology. It sees enemies everywhere around it, and while its leadership wishes ill on the United States, the application of Sharia in the caliphate and the expansion to contiguous lands are paramount. Baghdadi has said as much directly: in November he told his Saudi agents to "deal with the rafida [Shia] first … then al-Sulul [Sunni supporters of the Saudi monarchy] … before the crusaders and their bases."

The foreign fighters (and their wives and children) have been traveling to the caliphate on one-way tickets: they want to live under true Sharia, and many want martyrdom. Doctrine, recall, requires believers to reside in the caliphate if it is at all possible for them to do so. One of the Islamic State's less bloody videos shows a group of jihadists burning their French, British, and Australian passports. This would be an eccentric act for someone intending to return to blow himself up in line at the Louvre or to hold another chocolate shop hostage in Sydney.

A few "lone wolf" supporters of the Islamic State have attacked Western targets, and more attacks will come. But most of the attackers have been frustrated amateurs, unable to immigrate to the caliphate because of confiscated passports or other problems. Even if the Islamic State cheers these attacks—and it does in its propaganda—it hasn't yet planned and financed one. (The Charlie Hebdo attack in Paris in January was principally an al‑Qaeda operation.) During his visit to Mosul in December, Jürgen Todenhöfer interviewed a portly German jihadist and asked whether any of his comrades had returned to Europe to carry out attacks. The jihadist seemed to regard returnees not as soldiers but as dropouts. "The fact is that the returnees from the Islamic State should repent from their return," he said. "I hope they review their religion."

Properly contained, the Islamic State is likely to be its own undoing. No country is its ally, and its ideology ensures that this will remain the case. The land it controls, while expansive, is mostly uninhabited and poor. As it stagnates or slowly shrinks, its claim that it is the engine of God's will and the agent of apocalypse will weaken, and fewer believers will arrive. And as more reports of misery within it leak out, radical Islamist movements elsewhere will be discredited: No one has tried harder to implement strict Sharia by violence. This is what it looks like.

Even so, the death of the Islamic State is unlikely to be quick, and things could still go badly wrong: if the Islamic State obtained the allegiance of al‑Qaeda—increasing, in one swoop, the unity of its base—it could wax into a worse foe than we've yet seen. The rift between the Islamic State and al-Qaeda has, if anything, grown in the past few months; the December issue of Dabiq featured a long account of an al‑Qaeda defector who described his old group as corrupt and ineffectual, and Zawahiri as a distant and unfit leader. But we should watch carefully for a rapprochement.

Without a catastrophe such as this, however, or perhaps the threat of the Islamic State's storming Erbil, a vast ground invasion would certainly make the situation worse.