The deadliest domestic terror attack in Australia’s history is raising an uncomfortable question: Is there an Islamic State revival in Asia?

Despite years of counterterrorism successes and the group’s territorial collapse in Iraq and Syria, the assault at Sydney’s Bondi Beach highlighted a troubling reality: This radical ideology remains active across the region.

The father-and-son duo who gunned down 15 people celebrating a Jewish holiday on Dec. 14 are believed to have been radicalized by IS propaganda. The extremist network has expressed admiration for the shooting — and while not officially claiming responsibility has acknowledged the influence of their ideology on the gunmen.