The United Kingdom and Norway have signed a major defense agreement to protect from Russian submarines and potential attacks on submarine cables.

The combined fleet of at least 13 warships will “hunt Russian submarines and protect critical infrastructure in the North Atlantic," the UK government said.

The partnership comes after a Russian spy ship known to map subsea cables last month entered UK waters. The Yantar shone lasers at the British military pilots who were monitoring them.

There has been a 30 percent increase in Russian naval activity around UK waters over the last two years. The new patrols will cover those waters, as well as those around Iceland and Greenland.

"At this time of profound global instability, as more Russian ships are being detected in our waters, we must work with international partners to protect our national security," UK Prime Minister Keir Starmer said.

The partnership follows a September announcement for the UK to supply the Norwegian navy with at least five new warships in a £10bn ($13bn) deal.

The expanded partnership includes year-round training of the UK's Royal Marines in Norway, the Royal Navy adopting advanced Norwegian naval strike missiles, collaboration on Sting Ray torpedoes, joint wargames, the UK joining a Norwegian program to develop motherships for uncrewed mine hunting and undersea warfare systems, and the UK and Norway leading NATO’s adoption of autonomous systems in the High North.

"For over 75 years, the UK and Norway have stood shoulder-to-shoulder on NATO’s northern flank, defending Europe and keeping our people safe," UK Defence Secretary John Healey MP said.

"This partnership takes us further, making our nations more secure at home and strong abroad."