LONDON — A Russian spy ship fired lasers at British forces deployed to monitor the vessel after it entered U.K. waters, the defence secretary said Wednesday.

John Healey confirmed the Russian spy ship Yantar was deployed to British waters for the second time this year after doing so in January and was currently on the edge of the U.K.’s territorial waters. However, it was the first time lasers had been directed at RAF pilots.

The defense secretary said Britain deployed a Royal Navy frigate and Royal Air Force P8 planes to monitor and track the vessel, which he said was “designed for gathering intelligence and mapping our undersea cables.”

“The Yantar directed lasers at our pilots,” Healey said. “That Russian action is deeply dangerous.”

“My message to Russia and to [Russian President Vladimir] Putin is this: we see you. We know what you’re doing. And if the Yantar travels south this week, we are ready.”

Healey said the vessel was designed to “put and hold our undersea infrastructure and those of our allies at risk” by having “capabilities which can undertake surveillance in peacetime and sabotage in conflict.”

Asked about why lasers posed such a risk, the defense secretary said: “Anything that impedes, disrupts or puts at risk pilots in charge of British military planes is deeply dangerous.”

The navy’s rules of engagement had been changed so Yantar could be followed more closely, and military options were ready if the vessel changed course.

“I’m not going to reveal those, because that only makes President Putin wiser,” Healey said.