Defense · Security

—The shift. Armed groups in Colombia have gone from drone novices to skilled operators in barely two years.

—The escalation. An April attack used more than a dozen drones at once, a coordinated swarm rather than a lone strike.

—The weapon. Some drones are guided by thin fibre-optic cables, making them immune to the radio jamming armies rely on.

—The cost gap. Such drones can be delivered for a few hundred dollars, against the millions spent trying to counter them.