How would the crew know that "commercially available drones" had anything to do with the RN/UK Government?
Do a couple of "commercially available drones" look anything like as powerful as a large SSN suddenly surfacing close to you and how does a pair of drones achieve this;
"I authorised a Royal Navy submarine, strictly as a deterrent measure, to surface close to Yantar to make clear that we had been covertly monitoring its every move." said the UK Defence Secretary!