Last week, the caliphate finally dwindled down to that one alley, and on Saturday it vanished entirely.
The Syrian Democratic Forces sacked the Islamic State’s last minuscule barrio in the town of Baghuz, in eastern Syria, after a weekslong siege. “One street in one village” may overstate the size of that last patch. In a recent video attributed to the Islamic State, apparently from just days ago, the area looked like a small junkyard defended by vagrants. Several years back, the Islamic State circulated videos of its fighters living among swimming pools and well-stocked shops. In the junkyard videos, it looked as if no one had bathed for weeks. Many of the inhabitants hobbled around on crutches, and some of the few working vehicles were wheelchairs.
To see the Islamic State reduced to these indignities is a pleasure worth savoring. Now that we’ve savored it, though, it is time to confront the threat that remains — which is not merely, as President Trump claimed this weekend, “losers” who will “resurface” “on occasion.” It is a systemic threat.
More than 40,000 foreigners are thought to have traveled to territory controlled by the Islamic State, and most are missing. David Malet, a political scientist at American University who studies foreign fighters, told me recently that when such combatants have traveled to war zones in the past, they have died at a rate of about one-third. Even if we assume that, say, half of the Islamic State’s foreigner fighters are dead — after all, many joined the group to die — that leaves about 20,000 alive.
We have little idea where they are and seriously undercounted them in Baghuz. In recent weeks, Islamic State fighters and civilians have emerged from the town as if from a clown car, disgorged in ever more unbelievable numbers. The most astonishing sight over the past week may have been a video showing fighters who had surrendered, preferring captivity to martyrdom, in a line stretching more than 250 men long. Yet many more fighters may be hiding in the countryside than have turned themselves over or died in Baghuz.
The Islamic State has had years to prepare for this moment and for some time had signaled that it was resigned to eventually losing some or all of its territory. By May 2016, its spokesman, Abu Muhammad al-Adnani, was telling followers abroad not to bother traveling to Syria.
“If one of you wishes and strives to reach the lands of the Islamic State, then each of us wishes to be in your place to make examples of the crusaders, day and night, scaring them and terrorizing them, until every neighbor fears his neighbor,” he said in an audio message. Since then, some sympathizers had stayed in the shrinking caliphate, while others stayed abroad or slunk out of the doomed territory to perpetuate the group’s ideals and re-spawn it elsewhere.
To see how slinking is done right, they needed only look to their forefathers. The founders of the Islamic State consisted of Qaeda veterans who escaped destruction by the American military and Sunni tribes in Iraq. Tactical retreat served them well, and the Islamic State has not lost the institutional wisdom that allowed those men to survive and then recapture territory, first slowly, then in 2014 all at once. They succeeded by positioning themselves as guardians of Sunnis who did not trust the Shiite-led government in Baghdad or the Alawite-led one in Damascus. Neither Iraq nor Syria has restored Sunnis’ trust.
Of the more than 40,000 foreigners who joined the Islamic State, several thousand have returned to their home countries — not always to face prosecution. Some pessimists worry that these returnees constitute a fifth column, outwardly rehabilitated but secretly ready to attack on command. History suggests that our concerns should not be so narrow.
The danger comes not just from plotters but also from their ideas. The spread of Islamic State ideology long predated the declaration of a caliphate, and it happened quietly, through the efforts of remarkably few individuals. Returnees from jihad do not always fight again, but their passion can infect others. Arab veterans of the Afghan war in the 1980s influenced the generation that fought in Iraq. The number of returnees from the Islamic State now may dwarf them.
In a few years, even some of those convicted of terrorist offenses will be free again. (Remember, Europeans tend not to lock up people for as long as Americans do.) Consider John Walker Lindh, the American who fought for Al Qaeda in Afghanistan and was sentenced to 20 years in federal prison in 2002. He is scheduled for release in May and appears to have remained a devout extremist. Such ideas do not reliably dissolve with time. They sometimes become more concentrated. Prepare for a new wave of true believers, recruited by the old.
The Islamic State is like herpes: It can be managed but never cured. Syria is scabbing over, and it might begin to heal. Elsewhere, though, the condition is dormant at best. It will break out again.
By Graeme Wood
Mr. Wood is a staff writer at The Atlantic and the author of “The Way of the Strangers: Encounters With the Islamic State.”