What is ISIS-K, the terrorist group tied to Moscow concert hall attack and 2021 Abbey Gate bombing?

The U.S. has attributed Friday’s terrorist attack on the Moscow concert hall to ISIS-K, but who is this group, and what is their interest in Russia?

"The Islamic State is leveraging its network of jihadists throughout Central Asia to plot and execute attacks, such as the one in Moscow," Bill Roggio, senior fellow at the Foundation for Defense of Democracies and founding editor of "The Long War Journal," told Fox News Digital. 

"The Islamic State appeals to the less patient and more fervent jihadists who aren’t on board with Al Qaeda’s more strategic, long-term plan," Roggio added. 

Islamic State-Khorasan, known as ISIS-K, took credit for a deadly attack in Moscow that killed at least 133 people, leading to the arrest of 11 suspects — four of whom were directly involved with the attack. Russian President Vladimir Putin addressed the nation in a television broadcast about the "bloody, barbaric terrorist act" and declared March 24 a day of mourning. 

RUSSIA CONCERT HALL GOES UP IN FLAMES AFTER ATTACK INVESTIGATED AS TERRORISM

The State Department confirmed to Fox News that U.S. intelligence had information about a planned terrorist attack in Moscow — potentially targeting large gatherings, to include concerts — which prompted the agency to issue a public advisory to U.S. citizens in Russia. 

The U.S. government also shared this information with Russian authorities in accordance with its longstanding ‘duty to warn’ policy. It is not clear how much information the U.S. gave Russian officials beyond what was in the public warning. 

A massive blaze is seen over the Crocus City Hall on the western edge of Moscow, Russia, on Friday, March 22, 2024. Several gunmen burst into a big concert hall in Moscow and fired automatic weapons at the crowd, injuring an unspecified number of people and setting a massive blaze in an apparent terror attack days after President Vladimir Putin cemented his grip on the country in a highly orchestrated electoral landslide. (Sergei Vedyashkin/Moscow News Agency via AP) (Sergei Vedyashkin/Moscow News Agency via AP)

ISIS-K operates out of Afghanistan. U.S. intelligence in March collected evidence that indicated the group had been planning an attack on Moscow and had been active in Russia, The New York Times reported. The group was founded in 2015 by disaffected members of the Pakistani Taliban, according to the outlet. 

The group adheres to a more hardline interpretation of Islam than its rivals, causing an adversarial dynamic to develop with the Taliban, Al-Qaeda and similar groups. 

BIDEN USE OF HAMAS DEATH COUNT CHALLENGED BY PROMINENT STATICIAN, SAYS NUMBERS ‘AREN'T ACCURATE'

ISIS-K entered mainstream conversation after carrying out the bombing on the Abbey Gate at Kabul airport in 2021 during the U.S. military drawdown, killing 13 U.S. service members. The Taliban ultimately claimed to have succeeded in killing the ISIS-K terrorist responsible for directing the attack. 

Smoke rises from an explosion outside the airport in Kabul, Afghanistan, on Thursday, August 26, 2021. (AP Photo/Wali Sabawoon) (Copyright 2021 The Associated Press. All rights reserved.)

Once the Taliban had control of Afghanistan, and the U.S. military presence departed, ISIS-K gained a foothold and continued to grow: The Taliban fought back and managed to limit the group’s recruitment of former Taliban fighters and prevented them from seizing territory, but it went on to carry out significant operations. 

The group has a particular obsession with Russia, accusing the Kremlin of being responsible for significant numbers of Muslim deaths due to operations in Afghanistan, Chechnya and Syria over the past few decades. 

In this handout photo provided by the U.S. Air Force, flag-draped transfer cases line the inside of a C-17 Globemaster II on August 29, 2021, prior to a dignified transfer at Dover Air Force Base, Delaware. The fallen service members died while supporting non-combat operations in Kabul. (Photo by Jason Minto/U.S. Air Force via Getty Images) (Jason Minto/U.S. Air Force via Getty Images)

A senior U.S. official told Fox News Digital at the time that it remained "important" that the world "continues to seek to degrade ISIS-K and any threat it might try to pose. However, ISIS-K continued to stage attacks against targets throughout Central Asia over the following two years. 

ISRAEL LAUDS CONGRESS' BLOW TO UN AGENCY WITH ALLEGED HAMAS TIES AS INVESTIGATIONS CONTINUE

Gen. Michael Kurilla, leader of U.S. Central Command (CENTCOM), testified in March 2023 that ISIS-K would be able to carry out "an external operation against U.S. or Western interests abroad in under six months with little-to-no warning," but he stressed that attacking the U.S. would prove "much harder for them."

The Biden administration last year warned Iran of an impending attack, which ultimately occurred at the memorial ceremony for Iranian General Qasem Soleimani in January 2024. The twin bombings killed at least 94 people and injured 284 others, and ISIS-K quickly took credit for the attacks.

Russian Rosguardia (National Guard) servicemen leave a bus near the burning building of the Crocus City Hall on the western edge of Moscow, Russia, Friday, March 22, 2024.  (Sergei Vedyashkin/Moscow News Agency via AP)

ISIS-K also plotted to target embassies, churches, business centers and the FIFA World soccer tournament in Qatar, according to classified intelligence that leaked as part of Massachusetts Air National Guardman Jack Teixeira’s data dump on a Discord social media server. 

"Pentagon officials were aware in December of nine such plots coordinated by ISIS leaders in Afghanistan, and the number rose to 15 by February, says the assessment, which has not been disclosed previously," The Washington Post reported on the leak. 

CLICK HERE TO GET THE FOX NEWS APP

"ISIS has been developing a cost-effective model for external operations that relies on resources from outside Afghanistan, operatives in target countries, and extensive facilitation networks," the assessment continued. "The model will likely enable ISIS to overcome obstacles — such as competent security services — and reduce some plot timelines, minimizing disruption opportunities."

Counterterrorism officials in Europe also claimed to have stymied several ISIS-K plots in recent months, according to The New York Times.

Fox News Digital’s Michael Dorgan, Anders Hagstrom and Caitlin McFall and The Associated Press contributed to this report.