How much damage will a small UAV with 1-2kg of HE do to a warship? Especially when targeting systems like the radar or the exhaust. Or a medium sized UAV with 5-10kg of HE? Will we start to see UAV attacks like this on warships, even in peacetime? I will image that it will be hard to actually catch the person flying the drone, especially if there's no one controlling it and it's just an preplanned flight path.
Is an explosive payload even required?
Given the nature of the mission, we're talking about operating deep inside foreign soil. Even as a state sponsored actor, it won't be easy to set up a UAV swarm with multiple small explosive payloads without setting off anti-terrorism tripwires.
A UAV, diving into a radar or airplane at 100+ kmph, with a simple 2kg hardened steel penetrator, on the other hand should probably be capable of punching a hole in something as fragile as a radar or airplane fuselage and mission-killing the platform. Not destroy but enough to put it out of commission for a few days - which is plenty if it's a D-Day strike.
Supplying sleeper cells with a bunch of swarm UAVs and inert penetrators should be a lot simpler than a whole bunch of explosives.