Explainer: How dangerous is Afghanistan's Islamic State

The group is also known as ISK, or ISIS K

The Islamic State offshoot that Americans blame for coalesced in eastern Afghanistan six years ago, and rapidly grew into one of the more dangerous terror threats globally. Despite years of military targeting by the U.S.-led coalition, the group known as Islamic State Khorasan has survived to press more assaults as the United States and other NATO partners withdraw from Afghanistan, and as the Taliban return to power. President Joe Biden cited the threat of Islamic State attacks in sticking with a Tuesday deadline for pulling U.S. forces out of Afghanistan. U.S. General Frank McKenzie told a Pentagon news conference that officials believe fighters with Islamic State carried out Thursday's attacks, including a bomber believed to have slipped into the Afghan crowds outside airport gates controlled by U.S. service members.