When the Taliban took control of Afghanistan in 2021, counterterrorism experts were alarmed at the possible resurgence of Islamist terrorist groups within the country. This Special Report lays out why those concerns, particularly about the regional Islamic State affiliate known as Islamic State Khorasan Province (ISKP), were well-founded. The report discusses the likely trajectory of ISKP’s activities in South Asia and recommends measures to minimize potential threats to the West and build regional resilience to extremism.