As Britain's flagship aircraft carrier sailed through the waters of the Mediterranean last month, it found itself targeted by a Russian submarine monitoring activity in the region. HMS Queen Elizabeth, the largest and most powerful warship constructed for the Royal Navy, was leading a Carrier Strike Group (CSG) to the Indo-Pacific. The Russian predator – believed to be a Kilo-class diesel-powered attack submarine from the Black Sea fleet – was spying on the nine-vessel group as it passed Cyprus. Military might: HMS Queen Elizabeth and the Carrier Strike Group But it was not long before predator turned prey as naval chiefs scrambled two Merlin Mk2 submarine-hunting helicopters to drop high-tech sonobuoys into the water to listen for the distinctive sounds emitted by the sub.