The Royal Navy has said it is shadowing a Russian naval task group that appeared off the north east of Scotland at the weekend.
The frigate Admiral Gorshkov and three auxiliary ships are travelling south “close to UK territorial waters”.
Portsmouth-based destroyer HMS Defender began escorting the group on Saturday.
Similar incidents have happened over the years, including in November 2017 when a Russian destroyer and a tanker appeared in the Outer Moray Firth.
The following month the Admiral Gorshkov was shadowed by the Royal Navy as it passed through the North Sea.
Aircraft carrier Admiral Kuznetsov, a destroyer, two frigates, three oil tankers and an ocean-going tug were in the task group.
The vessels later left the firth, sailing into the Atlantic.
The latest incident involves the frigate and a tug, supply ship and a tanker.
HMS ‘Defender’ will continue to shadow the task group as passes through the English Channel.
Royal Navy Commander Richard Hewitt said: “We will continue to work with our allies to shadow Russian ships passing through international waters close to our shores, to ensure the Russian navy follows the correct protocol on its journey.”