Ukraine claimed it carried out an underwater drone strike on Dec. 15, the first such attack in maritime warfare, that critically damaged a Russian Kilo-class attack submarine at the Russian port of Novorossiysk,

Ukraine has used long-range drones to attack Russian oil platforms as it expands its strikes on the country's energy sector.

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.

At least two people have been killed in a drone attack in Russia’s Saratov region, according to local authorities.

The drones are still in limited supply and are not always the ideal interception method, Ukrainian soldiers and an official told Business Insider.