The Israeli security official noted that even with their current destructive potential, the munitions attached to such UAS today are in their relative infancy, not yet on a scale that any one of them alone could replicate a 9/11-style attack.

But they are rapidly approaching that threshold.

“They are becoming much more accurate in their capabilities of navigation,” the Israeli security official said. “I think where we will be seeing things is that the amount of explosives will get bigger now.”

Smaller commercial UAS have another unique advantage over traditional aircraft and missile platforms: They have no launch signature, making them far more difficult to detect. Used in greater numbers, known as a swarm, they’re also harder to intercept.