On 24 June 2025, a BBC Verify investigation revealed that a Russian warship, the Project 20380 corvette Boykiy, part of the Baltic Fleet, had used a false identification signal (AIS) as it passed through the English Channel on Saturday, 20 June. The ship, which is armed with guided missiles, was escorting two oil tankers, the Sierra and the Selva, part of Russia’s so-called “shadow fleet” used to transport sanctioned oil products, the BBC reported. On ship-tracking websites, the Boykiy appeared as a civilian vessel that had previously used the identifier, raising the suspicions of analysts.

BBC Verify established that the Boikiy was indeed behind the false AIS code after comparing satellite imagery, tracking data and video footage of the ship passing under the Great Belt Bridge in Denmark. The corvette, which was returning from a diplomatic mission in West Africa where it was spotted in the port of Conakry, Guinea, encountered the tankers at the entrance to the English Channel on June 20. The Sierra and Selva, which are under UK sanctions, had arrived from India via the Suez Canal and the Mediterranean. The Selva initially broadcast an AIS signal as a Panamanian vessel but later changed its flag to Palau, indicating an attempt to disguise its identity.

The “shadow fleet” in question is a network of tankers, often old and poorly maintained, used to circumvent Western sanctions on oil exports imposed after the conflict in Ukraine erupted in 2022. As Reuters notes, these vessels employ techniques such as reflagging, fake identities, and transhipping oil in international waters to make tracking difficult. According to Brookings, about 60% of the “shadow fleet” vessels were purchased from Western companies, mostly Greek, underscoring the difficulty of combating the practice.