Opinion | Islamic State: Landless but Still Dangerous

The “caliphate” also developed a perverse power to attract recruits, including many from developed nations. Many of these are now among the tens of thousands of captive ISIS men, women and children, often “unrepentant, unbroken and radicalized,” as Gen. Joseph Votel, the head of the United States Central Command, told Congress in March. Their fate poses a major problem for their captors. On Tuesday, President Trump complained anew that European countries were “refusing to take back prisoners from their specific countries;” he had warned earlier that if the Europeans didn’t do so, the captives might be simply released.

Ending direct ISIS control over a vast stretch of Syria and Iraq and their riches was a major feat, and a serious blow to the organization, but it is too early to proclaim, as Mr. Trump did in February, that the American-led coalition had wiped the Islamic State out “100 percent.” Untold thousands of ISIS fighters remain dispersed in cells from Africa to Asia, awaiting orders, as the bombers in Sri Lanka apparently did. Its caliphate gone, ISIS has gone back underground, where it will long keep the United States military and other armies busy, whether in Afghanistan, Africa, the Philippines, Syria, Iraq or elsewhere, as Times reporters detailed in a survey in March.

The counterinsurgency campaign remains critical, but alone it will not be enough to uproot ISIS or its offshoots. As Fawaz Gerges, the author of “ISIS: A History,” has argued, Islamist terrorism feeds on a deep sense of outrage and injustice that flourishes in the broken politics of the Arab and Islamic world, the clash of Sunni-dominated Saudi Arabia and Shiite-majority Iran, and the intervention of outside powers like the United States, Russia and Turkey.

A long-term strategy must include seeking an end to those rivalries, tensions and conflicts. So long as they continue to boil, Mr. al-Baghdadi, or whatever preening jihadist succeeds him, will be back.

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