Britain's defence minister has said that Russia’s Yantar, observed in the waters north of Scotland, is used for gathering intelligence and mapping undersea cables.
In Russia, its official mission is described as purely civilian.
The ship, which was built at the Yantar shipyard in Kaliningrad - Russia’s enclave on the Baltic Sea - is officially described as an oceanographic research vessel intended for deep sea research and search and rescue operations.
Yantar’s operation is handled by the so-called Main Directorate of Deep-Sea Research of the Ministry of Defense, known as GIGU, and is widely regarded as the Kremlin’s top-secret spy agency.
Britain has called it "the military agency leading the development of Russia’s underwater intelligence gathering operations" and imposed sanctions on the body in June.
The Financial Times described GIGU’s operations as "so classified that only a small group of highly trained Russian hydronauts are privy to them."
Official details about the ship are scarce, but its specifications have been widely described in Russia’s specialised media.
The 108 metre-long vessel, commissioned in 2015, is operated by a 60 person crew and can remain autonomous at sea for at least two months, though longer journeys have been reported.
The Yantar carries two autonomous manned underwater vehicles, "Rus" and "Consul," capable of working at a depth of 6,000 metres.
Some of the search operations such submersibles could be involved in include locating and recovering debris of sunken vessels and aircraft. For instance, in January the Yantar was seen at the site of the sinking of Russia's cargo ship "Ursa Mayor" in the Mediterranean Sea, between Spain and Algeria.
Western officials believe that submersibles on the Yantar are surveilling and mapping the seabed infrastructure, possibly looking for vulnerabilities, while also having the capability to damage underwater cables.
It is also understood that a number of unmanned underwater devices are onboard the Yantar, often described as "underwater drones."
Tech media in Russia claim that the country has every chance of "gaining the lead in the global race" for developing such devices, with several research institutes and construction bureaus tasked with developing underwater drones.
The Yantar is not the only "oceanographic research" vessel Russia currently operates.
It is the lead ship of "project 22010" built by the same shipyard in Kaliningrad. The project also includes the 2012 "Seliger" and the newest vessel, "Evgeny Gorigledzhan", commissioned in 2022.
Danish media reported that the latter was "able to sail completely undisturbed in Danish waters" in October 2023.
The production of one more such ship, "Almaz", is due to be finished in November 2026, as Russia’s military production booms.
Russia’s embassy in London dismissed the UK’s warnings of espionage as "militaristic hysteria", adding that Moscow has "no interest in British underwater communications."
Deputy chairman of the Defence Committee in Russia’s parliament Aleksey Zhuravlev told news site Gazeta.ru that "it’s absolutely clear who is escalating – and it’s not Yantar’s crew, who are simply engaged in drawing up nautical charts".
