What is ISIS-K, the group that claims it carried out the Moscow concert attack?

The death toll from an attack on a concert hall in Moscow continues to rise. U.S. officials say they believe an organization known as ISIS-K, or the Islamic State Khorasan Province, carried out the strike. The group claimed responsibility on Friday, posting on the social media platform Telegram.

What is ISIS-K?

ISIS-K emerged in 2014 and 2015 in Afghanistan and neighboring Pakistan, after its leaders broke away from al-Qaida and the Taliban.

Its fighters declared loyalty to the even more violent and extremist Islamic State, also known as ISIS, which was gaining influence at the time, mounting attacks in Iraq and Syria, as well as against targets in the West.

"ISIS Khorasan was one of the first branches [in central Asia] to pledge allegiance to ISIS," said Asfandyar Mir, a senior expert at the United States Institute of Peace.

According to Mir, the group has sought to distinguish itself among jihadi fighters by adopting a radical Islamic worldview more militant and uncompromising than its rivals, including al-Qaida and the Taliban.

In August 2021, ISIS-K carried out a deadly attack at the Kabul airport in Afghanistan that killed more than 150 Afghan civilians and more than a dozen U.S. service members.

The group's leaders are still based largely in eastern Afghanistan and Pakistan.

But according to experts at the Center for Strategic and International Studies (CSIS), the group has been working to expand its operations across the "Khorasan" region, a historical term that encompasses parts of Central Asia, Afghanistan, Iran and Pakistan.

Why attack Russia now?

Some experts said they're still waiting for further confirmation that ISIS-K perpetrated the attack outside Moscow, but they agreed Russia has long been a major target for the group.

"Russia is at times equivalent or a greater enemy [for ISIS-K] than the United States," said Daniel Byman, a senior fellow at CSIS and a professor at Georgetown University who has long studied ISIS.

Russia was an ally of Syria's government in the war against ISIS and Moscow has developed closer ties to the Taliban in Afghanistan, angering ISIS leaders.

According to Byman, hatred of Russia also remains intense among jihadists who fought Russia's army in Chechnya in the 2000s. He said the timing of the attack could simply reflect the fact that ISIS-K operatives were in place.

"It might simply be that the attack was ready ... and this was a good time to go," he said.

Is there a link between ISIS-K and Ukraine?

Russian officials say 11 people, including four alleged gunmen, are in custody.

In a televised address on Saturday, President Vladimir Putin suggested a link between the attackers and Ukraine.

"They tried to hide and moved towards Ukraine, where, according to preliminary data, a window was prepared for them on the Ukrainian side to cross the state border," Putin said.

After invading Ukraine two years ago, Russia is waging a full-scale war against its neighbor.

Ukrainian officials denied any involvement. On Saturday, a spokeswoman for the U.S. National Security Council said Ukraine was not involved.

"ISIS bears sole responsibility for this attack. There was no Ukrainian involvement whatsoever," Adrienne Watson, the NSC spokeswoman said.

According to Byman, there is no known connection between ISIS-K and Ukraine. "To my knowledge, none whatsoever," he told NPR.

Who are ISIS-K's other enemies?

Just about everybody. Experts say many jihadist groups focus their ambitions on certain targets and emerge as the clients of major national powers.

But ISIS-K is fighting or has declared hostilities against Al Qaeda, China, Iran, Pakistan, Russia, Syria, the Taliban and the United States.

ISIS-K has "shown they can take on major powers and survive," Byman said. "They get support and financial contributions from wealthy individuals in the Islamic world."

While elements of ISIS have suffered major military setbacks in recent years, losing territorial gains in Afghanistan, Iraq and Syria, they have continued to attract recruits.

Bragging rights after an "audacious" attack

According to experts, a high-profile attack on Moscow would also be viewed as a major accomplishment within the wider jihadi world, potentially allowing ISIS-K to recruit more fighters and financial support.

"ISIS-K has been seeking to outperform rival jihadi groups," said Asfandyar Mir at the United States Institute of Peace.

"By carrying out more audacious attacks it really distinguishes its jihadi brand and asserts leadership as a jihadi vanguard."

"Part of how these groups compete is to show that they're active and they're part of the struggle," agreed Byman. "Groups are in competition with each other and the result is more violence."

Is ISIS-K a threat elsewhere?

Despite military and territorial setbacks, ISIS-K has been expanding its ambitions and operations, experts told NPR.

"There have been reports of active and foiled ISIS-K plots in Europe," Mir said. "[The organization] really has a global mission of going after all entities that it considers as being opposed to its brand of Islamism."

"Most of its attacks until recently were largely confined to Afghanistan and Pakistan, but it carried out a major attack in Iran earlier this year that was incredibly devastating," Byman said.

U.S. officials have been warning that the group is extending its reach and said they issued a specific alert "in early March" to Russian officials about a "planned attack."

"That warning is quite significant," Byman said. "If it had any degree of specificity, Russia should have been better prepared."