ISIS has the “mandate to attack across the Atlantic” and ISIS-K is one of its affiliates that has been “tasked to do that,” the official said.

“ISIS, as a violent extremist organization has been successful in exploiting social media and looking at people that are on social media and very quickly reaching out to them and using that as a medium to bring them in the organization,” Votel said.

“I think they have a very sophisticated way of recruiting. We certainly have seen that in Iraq and Syria and we see it here,” Votel added.

The warnings about the threat posed by ISIS-K comes as the terror group is on the cusp of being driven from its last bastion in Syria.

While the two affiliates share an ideology and tactics, the depth of their relationship with regards to organization and command and control has never been entirely established.

The US intelligence official said that the membership of ISIS-K includes “a small number of veteran jihadists from Syria and other foreign terrorist fighters,” saying that the US has identified 10 to 15 of their top operatives in Afghanistan.

US officials have previously expressed concerns that as ISIS losses its last strongholds in Syria, its fighters may seek to flee to other affiliates in places like Afghanistan.

Votel said that the membership of ISIS-K “reflects more of a local South Asia flavor and includes some elements of foreign fighters but also includes some elements of people that are local to the area here.”

ISIS-K has established itself in remote areas in Afghanistan’s mountainous eastern provinces and the official said that the Afghanistan affiliate “doesn’t need large swathes of land like ISIS in Iraq and Syria does.”

The head of US Special Operations Command, Gen. Raymond “Tony” Thomas told the Senate Armed Services Committee earlier this month that the US military has “made huge progress against ISIS-K which is the primary external threat in Afghanistan.”

The US has killed several ISIS-K leaders in recent years and has conducted numerous airstrikes and raids targeting the terror group in its redoubts in eastern Afghanistan.

The Taliban has also fought ISIS as the two anti-government groups compete for territory and recruits.

Despite those battlefield successes, US officials would not say how many fighters are currently in ISIS-K.

A Pentagon Inspector General report on the US military mission Afghanistan said that “as of September 2018, it estimated that there were fewer than 2,000 ISIS-K fighters in Afghanistan.”

“We conducted operations against them for some period of time and I think we’ve had a good disruptive impact on them, they operate in areas that are extraordinarily remote, difficult to get into and you have that challenge here in Afghanistan with mountains and some of the rugged terrain that exists here in Afghanistan,” Votel said.

And despite nascent negotiations between the US and the Taliban regarding a potential peace settlement in Afghanistan, Votel said that the US has vested interests in combating international terror groups like ISIS.

“The fact of the matter is that we have an enduring interest here to make sure that violent extremist groups in this part of the world can’t be used to hurt Americans, American interests and American homeland,” he said.