Bangladesh, April 29 -- By any serious measure, Bangladesh has spent the better part of two decades trying to outrun the ghosts of militancy. From the rise of Jamaat-ul-Mujahideen Bangladesh (JMB) to the horrors of the Holey Artisan Bakery attack in 2016, the country has learned—often painfully—that extremism rarely arrives announcing itself. It comes disguised: as charity, as religious instruction, as student activism, as online grievance, and now, if recent allegations are correct, as martial arts training.

That should alarm every Bangladeshi parent, teacher, police officer, and policymaker.

According to the information, an organization calling itself Fatah Combat System (FCS) has been operating in several districts under ...