Britain deployed its armed forces to deter Russian submarines from attacking its cables and pipelines when they spent around a month in British waters earlier this year, Defence Secretary John Healey said on Thursday.

Healey said British forces and allies including Norway tracked and deterred malign activity by the Russian vessels, and said he was making the operation public so President Vladimir Putin would know that they had been detected.

He said the submarines had now left British waters and headed north, and there were no signs of damage to underwater infrastructure.

“To President Putin, I say ‘We see you. We see your activity over our cables and our pipelines, and you should know that any attempt to damage them will not be tolerated and will have serious consequences’.”

“Our armed forces left them in no doubt that they were being monitored, that their movements were not covert, as President Putin planned, and that their attempted secret operation had been exposed”.

Healey said the Russian operation involved an Russian Akula class attack submarine and two specialist submarines from Moscow’s Main Directorate for Deep Sea Research (GUGI).