Drones as sonar probes and electronic decoys

Could drones overwhelm submarine sensors or confuse radar-guided attacks?

Potentially, but active sonar exposes the user as well; drones are more plausibly useful as distributed electronic-warfare and deception tools when employed in numbers.

The answer warns that an active-sonar drone can help locate a submarine while also announcing the emitter to every capable listener. Moving the source away from a ship can complicate the enemy's response, but it does not make active transmission covert. Swarms may be more useful for creating false or confusing electronic signatures for radars and seekers. In both cases, the operational purpose and the information revealed to the enemy matter more than the novelty of using an unmanned platform.