U.K. and Norway led a military operation to deter Russian submarines in the North Atlantic

British and Norwegian militaries led a weekslong operation to deter Russian submarines suspected of "malign activity" in the North Atlantic, the U.K. said.

LONDON — British and Norwegian militaries led a weekslong operation to deter Russian submarines suspected of "malign activity" in the North Atlantic, the U.K. military said Thursday.

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Defense Secretary John Healey said a frigate, planes and hundreds of personnel monitored a Russian attack sub and two spy submarines near undersea infrastructure north of the U.K. He said the Russian vessels eventually left after the operation that lasted more than a month.

Healey said his message to Russia was "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."