JAKARTA: Indonesians are joining the procession of jihadists to Syria and Iraq, sparking fears they will revive sophisticated militant networks when they return and undermine a decade-long crackdown that has crippled the most dangerous cells.

Support for groups like the Islamic State of Iraq and the Levant (ISIL), Sunni radicals currently rampaging through northern Iraq, is growing among Indonesian extremists with dozens believed to have joined the insurgency.