On February 3, American special forces surrounded the hideout of Islamic State’s current caliph, Abu Ibrahim al-Hashemi al-Qurashi, who blew himself up with his family to avoid capture. Born in a Turkmen-majority village in northern Iraq, the late caliph was likely involved with a jihadist network known as the Qaradash, which was active in the area even before the fall of Saddam Hussein. Hassan Hassan explains the significance of Qurashi’s origins for the future of IS as a whole:

This [Qaradash] network comes largely from the areas around the Turkmen-dominant border town of Tal Afar in northern Iraq. Because of the demography of this longtime jihadist incubator, it has often been assumed that any member of Islamic State who hailed from Tal Afar was Turkmen rather than Arab. As such, because [IS] emphasizes the need for its leaders to be of a specific lineage linked to the prophet Mohammad, a Turkmen could never become head of the organization even though the Afaris have always had an outsized influence within and on Islamic State.

Indeed, it is almost certain that official IS documents invented an Arab lineage for Qurashi—a sign, to Hassan, of the group’s desperation to find a new leader after the U.S. eliminated the previous caliph, Abu Bakr al-Baghdadi, in 2019.

Because Islamic State has been weakened, its options for leaders are limited and it has had to rely on a small pool of candidates it can trust, notwithstanding the inconvenience of having to prove they are of Arab background. . . . It’s hard to imagine Islamic State will venture outside the “Qaradashians” for its new leader.

Add to these internal problems a broader set of factors favoring its enemies, including the growing strength of rival groups and governments, and the weakening of the international jihadist movement writ large, and it becomes clear how the organization’s chances of recovery are currently slim.

The death of its leader under these circumstances will further disorient the group and weaken its ability to focus on international terrorism. In other words, the prospects for the group do not seem as promising as suggested by much of the media commentary that followed Islamic State’s operation two weeks ago in northern Syria, in which it attacked a prison controlled by the U.S.-backed Kurdish forces and freed some jailed leaders.

When the IDF finally caught up with the late Hamas leader Yahya Sinwar, he wasn’t deep inside a subterranean lair, as many had expected, but moving around the streets the Rafah. Israeli forces had driven him out of whatever tunnel he had been hiding in and he could only get to another tunnel via the surface. Likewise, Israel hasn’t returned to fight in northern Gaza because its previous operations failed, but because of its success in forcing Hamas out of the tunnels and onto the surface, where the IDF can attack it more easily. Thus maps of the progress of the fighting show only half the story, not accounting for the simultaneous battle belowground.

At the beginning of the war, various options were floated in the press and by military and political leaders about how to deal with the problem posed by the tunnels: destroying them from the air, cutting off electricity and supplies so that they became uninhabitable, flooding them, and even creating offensive tunnels from which to burrow into them. These tactics proved impracticable or insufficient, but the IDF eventually developed methods that worked.

John Spencer, America’s leading expert on urban warfare, explains how. First, he notes the unprecedented size and complexity of the underground network, which served both a strategic and tactical purpose:

The Hamas underground network, often called the “Gaza metro,” includes between 350 and 450 miles of tunnels and bunkers at depths ranging from just beneath apartment complexes, mosques, schools, hospitals, and other civilian structures to over 200 feet underground. . . . The tunnels gave Hamas the ability to control the initiative of most battles in Gaza.

One elite unit, commanded by Brigadier-General Dan Goldfus, led the way in devising countermeasures:

General Goldfus developed a plan to enter Hamas’s tunnels without Hamas knowing his soldiers were there. . . . General Goldfus’s division headquarters refined the ability to control forces moving underground with the tempo of the surface forces. Incrementally, the division refined its tactics to the point its soldiers were conducting raids with separate brigades attacking on the surface while more than one subterranean force maneuvered on the same enemy underground. . . . They had turned tunnels from obstacles controlled by the defending enemy into maneuver corridors for the attacker.

This operational approach, Spencer explains, is “unlike that of any other military in modern history.” Later, Goldfus’s division was moved north to take on the hundreds of miles of tunnels built by Hizballah. The U.S. will have much to learn from these exploits, as China, Iran, and North Korea have all developed underground defenses of their own.