> suicide quadcopter RC drones (carrying e.g. grenades); and other extremely-low-cost impossible-to-restrict solutions to “leverage” ordinary weapons grenades

> suicide quadcopter RC drones (carrying e.g. grenades); and other extremely-low-cost impossible-to-restrict solutions to “leverage” ordinary weapons grenades are illegal to own for a civilian in the US, so that situation isn't that hard to restrict. Sure IEDs are a thing, but not quite as easy or low cost.