"We see you," was the provocative warning issued by British Defense Minister John Healey to Russian President Vladimir Putin after a Russian spy ship was spotted in British waters this week.
Known as "Yantar," it is operated by the Russian Ministry of Defense and is officially engaged in oceanographic research. However, Western officials believe the vessel is used for deep-sea espionage.
"Yantar" is well-known among European governments and is typically accompanied by their naval commands.
However, the ship's recent passage through European waters coincided with a challenging time: NATO is increasing its military presence in the Baltic after a power cable was damaged there over Christmas. An oil tanker, suspected to be part of the Kremlin's shadow fleet violating sanctions, has become the focus of the investigation.
This incident follows a series of similar occurrences that are believed to have resulted from sabotage. This has heightened concerns that Europe's underwater communication cables, gas pipelines, and energy infrastructure are vulnerable targets in Russia's hybrid warfare.
The Euronews fact-checking team investigates what we know about the "Yantar" ship and its activities.
What do we know about the "Yantar" ship?
"Yantar" has been operating for the Russian underwater research agency GUGI since 2015.
GUGI is considered a secret division. Originally established as part of the Russian Navy, it now operates independently in the interests of the Ministry of Defense. In addition to "Yantar," it includes several specialized submarines, some of which are nuclear-powered.
"Yantar" is specifically designed for gathering intelligence. It can lay and retrieve objects from the seabed. The ship is also equipped with crewed deep-sea submarines capable of descending to depths of 6,000 meters, along with deep-sea robots attached to the vessel.
OSINT analyst H.I. Sutton, who specializes in submarines and underwater systems, described the ship as "a special, unique" mother ship.
"Yantar, as I believe, was intended for conducting operations on the seabed that do not require the exclusive stealth of submarines, and it can do this much more cheaply," he explained.
"Yantar" is equipped with electronic sensors for mapping the seabed and a communication dome, indicating that it is likely used for mapping the network of critical pipelines and cables that connect Western countries.
When did the vessel enter British waters and why was it pursued by the Royal Navy?
"Yantar" was first spotted on Monday, 45 miles (83.3 km) off the British coast, in the UK's exclusive economic zone (EEZ).
According to an analysis of vessel tracking data conducted by Euronews, it passed through the English Channel on Tuesday, heading east towards the waters of Belgium and the Netherlands.
After passing through the English Channel, the ship approached Atlantic Crossing 1, an underwater telecommunications cable linking the US to the UK, the Netherlands, and Germany.
By Friday, the vessel was located in the Kattegat strait between Denmark and Sweden, according to maritime tracking data, suggesting it was heading back to its base in St. Petersburg.
On Wednesday, the UK dispatched two Royal Navy ships, HMS Somerset and HMS Tyne, to monitor "Yantar." The Ministry of Defense stated that it had "changed the rules of engagement" to allow the ships to approach the vessel.
Experts say that escorting Russian vessels through European waters is a normal occurrence. However, it was highly unusual for a Royal Navy submarine to be allowed to surface near the Russian ship.
"I can't recall this happening before. This is not something typically advertised to your adversaries," said Mike Plankett, a naval expert from Janes Intelligence, to Euronews. "I think this was a message to the Russians: We know what you are doing with this ship. We are watching you."
The British Defense Minister stated that the vessel was a "spy ship" used for "mapping critical underwater infrastructure in the UK."
This marks the most pointed public rhetoric from any European government regarding "Yantar's" intelligence-gathering operations.
Where else has it been spotted in European waters?
In November, "Yantar" was expelled from Irish and British territorial waters after being spotted "drifting over critical underwater infrastructure in the UK," according to the British Defense Minister.
Later in November, the ship was found to have entered the Mediterranean Sea through the Strait of Gibraltar and stopped in the port of Algeria.
Then "Yantar" was dispatched to investigate the sunken MV Ursa Major, a Kremlin-linked cargo vessel that sank in the Mediterranean Sea between Spain and Algeria after an onboard explosion on December 23.
It is believed that Ursa Major was transporting weapons from Syria, where the Kremlin-backed President Bashar al-Assad was overthrown earlier in December, raising questions about the future of Russian military bases in the country.
The ship's owner, closely tied to the Kremlin, labeled this a "terrorist act."
Naval analysts consider the sinking of Ursa Major suspicious. While little is known about "Yantar's" mission to inspect the damage, naval analyst Sutton suggests that it was likely collecting evidence of the ship's sinking and possibly "retrieving or destroying" sensitive equipment.
Could the information collected by "Yantar" be used for future sabotage?
There is no declassified information confirming that "Yantar's" mapping operations were used in alleged acts of sabotage when vessels anchor on the seabed in an attempt to sever cables.
However, "Yantar's" dubious activities and the frequency of alleged sabotage incidents mean that Europe is increasingly vigilant regarding the Russian threat.
In April of last year, a critical underwater communication cable to a Norwegian airbase in the Arctic was damaged. In November, two cables were severed in the Baltic Sea, including the only underwater data cable connecting Finland to Central Europe.
The investigation into the latest alleged sabotage, which damaged the Estlink-2 cable in the Baltic Sea over Christmas, focused on an oil tanker believed to be part of the so-called shadow fleet of Russia.
While the Washington Post, citing Western officials, reported that it was likely an accident, European politicians hinted at a deliberate act of sabotage orchestrated by Moscow.
"I think it's unlikely that all of these (incidents) were coincidental. Something is happening there, whether it's a targeted campaign or just a test to see if it's possible to sever a cable with an anchor," said Mike Plankett from Janes Intelligence.
Ownership, management, and flags of the shadow fleet are opaque, making it difficult for Western authorities to investigate or track control over its vessels.