The Russian submarine was allegedly carrying Kalibr cruise missiles, which Russia has used in devastating strikes on critical infrastructure and military targets across Ukraine. The SBU said the submarine was “put out of action” as a result of the blast. The FT could not independently verify the claim.

The Royal Navy says it has tracked a Russian submarine through the English Channel to "safeguard" UK waters. A tanker shadowed the Russian Kilo-class submarine Krasnodar as it sailed on the surface from the North Sea, through the Strait of Dover and into the English Channel, it said.

Russia’s Kilo-class submarines may be Cold War designs, but they remain at the core of Moscow’s conventional undersea fleet. -Nicknamed “Black Holes” for their extreme quietness, modern Project 636.6 Improved Kilos combine diesel-electric stealth with long-range Kalibr cruise missiles,