ISIS-K: What to know about Taliban rival seen as threat to Afghanistan evacuation

The United States has fought against the Taliban, al Qaeda, and the Haqqani insurgent groups in Afghanistan for the last two decades, but counter-terrorism experts warn that the imminent threat ISIS-K poses could prove catastrophic.

The insurgent group formed after a faction within the Taliban splintered and pledged allegiance to Abu Bakr al-Baghdadi – the leader of the Islamic State in Iraq and Syria – in October 2014. By 2015 the offshoot ISIS-K became formally recognized as a terrorist organization, Katherine Zimmerman, a fellow in foreign and defense policy for the American Enterprise Institute, told Fox News.