The British navy said Wednesday that is ramping up measures to protect its waters from secret Russian operations after identifying a Russian spy vessel in UK waters for the second time in weeks.

The British defense secretary told Parliament that the Yantar, which he described as a Russian spy ship, had come near Britain’s coast for the second time in a few months.

The Royal Navy of the United Kingdom has been closely tracking a Russian spy ship recently spotted in British waters, sparking concerns about Russia’s activities near the U.K.’s critical underwater infrastructure.