The ISIS affiliate that American officials say was behind the deadly attack in Moscow is one of the last significant antagonists that the Taliban government faces in Afghanistan, and it has carried out repeated attacks there, including on the Russian Embassy, in recent years.

That branch of ISIS — known as the Islamic State Khorasan or ISIS-K — has portrayed itself as the primary rival to the Taliban, who it says have not implemented true Shariah law since seizing power in 2021. It has sought to undermine the Taliban’s relationships with regional allies and portray the government as unable to provide security in the country, experts say.

In 2022, ISIS-K carried out attacks on the Russian and Pakistani embassies in Kabul and a hotel that was home to many Chinese nationals. More recently, it has also threatened attacks against the Chinese, Indian and Iranian embassies in Afghanistan and has released a flood of anti-Russian propaganda.

It has also struck outside Afghanistan. In January, ISIS-K, carried out twin bombings in Iran that killed scores and wounded hundreds of others at a memorial service for Iran’s former top general, Qassim Suleimani, who was killed by a U.S. drone strike four years before.

In recent months, the Taliban’s relationship with Russia, as well as China and Iran, has warmed up. While no country has officially recognized the Taliban government, earlier this month Russia accepted a military attaché from the Taliban in Moscow, while China officially accepted a Taliban ambassador to the country. Both moves were seen as confidence-building measures with Taliban authorities.

ISIS-K has both denounced the Kremlin for its interventions in Syria and condemned the Taliban for engaging with Russian authorities decades after the Soviet Union invaded Afghanistan.

Its propaganda has painted the Taliban as “betraying the history of Afghanistan and betraying their religion by making friends with their former enemies,” said Ricardo Valle, the director of research of the Khorasan Diary, a research platform based in Islamabad.

In the more than two years since they took over in Afghanistan, Taliban security forces have conducted a ruthless campaign to try to eliminate ISIS-K and have successfully prevented the group from seizing territory within Afghanistan. Last year, Taliban security forces killed at least eight ISIS-K leaders, according to American officials, and pushed many other fighters into neighboring Pakistan.

Still, ISIS-K has proved resilient and remained active across Afghanistan, Pakistan and Iran. Within Afghanistan, it has targeted Taliban security forces in hit-and-run attacks and — as it came under increasing pressure from Taliban counterterrorism operations — staged headline-grabbing attacks across the country. Just a day before the attack at the concert hall in Moscow, the group carried out a suicide bombing in Kandahar — the birthplace of the Taliban movement — sending a powerful message that even Taliban soldiers in the group’s heartland were not safe.

After the attack in Moscow, Abdul Qahar Balkhi, a spokesman for Afghanistan’s foreign ministry, said in a statement on social media that the country “condemns in the strongest terms the recent terrorist attack in Moscow” and “considers it a blatant violation of all human standards.”

“Regional countries must take a coordinated, clear and resolute position against such incidents directed at regional de-stabilization,” he added.