As the U.S. continues to work towards completing its withdrawal from Afghanistan to meet its Aug. 31 deadline, it is already operating in uncomfortably close proximity to the Taliban militant group.

At the same time as U.S. officials and commanders keep one eye on their enemy of the last two decades, the other eye is warily watching a shared enemy in the country called ISIS-Khorasan.

On Wednesday, CNN reported that U.S. defense officials were concerned with what they call a “very specific threat stream” from this group. The official warned that they were familiar with intelligence that suggests the militants are planning to take advantage of the chaos around Kabul’s international airport by planning attacks on the site.

Known as ISIS-K, the group is a branch of the more notorious Islamic State in Iraq and Syria (ISIS) that terrorized the world in the last decade through its violent rise during Syria’s civil war, its brutal propaganda, and its capacity to inspire lone-wolf attackers in the West. This particular branch is named for the historic region of Khorasan, which connects the Middle East with South and Central Asia.

This branch of ISIS first emerged in 2015, according to the Center for Strategic and International Studies (CSIS) think tank in Washington D.C. Like other offshoots of the group, its ranks consist of members from a variety of pre-existing militants from the region mixed with a combination of foreign fighters and leaders sent from ISIS’ leadership in Iraq and Syria to Afghanistan. Since its inception, ISIS-K has conducted scores of deadly attacks that have been concentrated in Afghanistan and Pakistan.

The threat from ISIS-K is nothing new to U.S. officials in Afghanistan. Between 2016 and 2018, U.S. forces eliminated four of its leaders including its founding emir, Pakistani national Hafiz Saeed Khan. ISIS-K was also the target of the U.S. military's first-ever deployment of its largest conventional ordinance, the GBU-43 "Mother of All Bombs" (MOAB), on a cave used by its fighters in Afghanistan’s Nangarhar Province. An Afghan government spokesman after the strike said that it killed 94 militants.

For the Taliban, ISIS-K is no friend. Since its arrival in Afghanistan, ISIS-K has recruited several former Taliban fighters into its ranks and its presence directly undermines their claim to leadership over Afghanistan. Like its counterparts in other parts of the region, ISIS-K looks to exploit sectarian tensions in Afghanistan by targeting members of the Hazara Shiite minority. According to the Countering Terrorism Center at West Point, the Taliban has clashed openly with ISIS-K, which in turn derides the Taliban as "filthy nationalists."

Pressure on ISIS-K cost it territory and fighters over the years, but U.S. officials told Voice of America in July that the group’s still capable of conducting attacks against Kabul or other targets. Another counterterrorism official in the region warned CNN that hundreds of ISIS-K prisoners may have escaped from jails in Bagram or Pul-e-Charkhi amid the Taliban’s advance.

These concerns have figured into more recent remarks by both U.S. and Taliban officials to justify their current operations at Kabul airport.

President Joe Biden specifically referred to the threat from ISIS-K to defend his decision to adhere to the Aug. 31 deadline.

“Every day we’re on the ground is another day we know that ISIS-K is seeking to target the airport and attack both US and allied forces, and innocent civilians," Biden said from the Roosevelt Room on Tuesday.

As for the Taliban, a spokesman did not refer to the group directly, but acknowledged the possibility that Kabul’s airport could be targeted by “ill-wishers.” The spokesman used this to warn Afghans from attempting to enter the airport, a position the Taliban has doubled down on as it seeks to prevent more exits from the country.

"There have been reports that some ill-wishers want to disrupt the security situation there by attacking and harming people and the media. So don't go close to the airport to avoid being hurt," a spokesman said of the threat, according to CNN.