The horrific bombing outside of Kabul airport that killed 13 U.S. troops and up to 75 Afghan civilians was the work of the Islamic State – Khorasan (ISIS-K). The group is an offshoot of ISIS which had occupied parts of Syria and Iraq in a self-described “caliphate.”

The attack on Thursday began when ISIS-K terrorists detonated suicide devices, one near the Abbey Gate of the airport and another at the nearby Baron Hotel. Gunmen were also involved in the violence.

There had previously been numerous warnings that such an attack could take place. 

While the name of ISIS-K might not be very familiar to the average American, it is quite well-known to U.S. and allied counterterrorism forces who have been attacking the group within the borders of Afghanistan for quite some time.