Through the Ukraine War, the Russian Navy has lost over 20 warships, submarines, landing ships, patrol boats, and support vessels, including its flagship, the Moskva guided-missile cruiser.
Last week, the Ukrainian security services landed a major victory when an underwater suicide drone hit a Russian attack submarine at port.
Now, the post-battle assessment is out, and, according to Western intelligence estimates, the Russian submarine suffered significant damage and is out of action.
A Russian Submarine Is Out of Action
Overnight on December 14-15, the Ukrainian security services (SBU) used an underwater suicide drone to penetrate the Russian defenses in the port of Novorossiysk Naval Base and strike the docked B-271 Kolpino, a Kilo-class attack submarine.
“The strike, utilising, a ‘Sub Sea Baby’ has likely resulted in significant damage to the submarine, leaving it unable to sail of its own accord or deploy,” the British Ministry of Defense assessed in its latest intelligence update on the Ukrainian conflict.
“As of 18 December 2025, open source reporting indicates the submarine as still docked in port in the same position it was at the time of the strike, and that other Russian vessels have dispersed from Novorossiysk Naval Base as a cautionary measure to mitigate against potential further Ukrainian strikes,” the British Ministry of Defense stated.
In the video of the attack, several other warships can be seen docked in port. Had the Ukrainians attacked with additional Sea Baby suicide drones, casualties could have been much higher for the depleted Russian Black Sea Fleet.
“Ukraine’s successful strike, penetrating Novorossiysk’s multi-layered defences, emphatically demonstrates the rapidly developing proficiency and capability of Ukraine’s maritime forces, particularly utilising uncrewed systems,” the British Ministry of Defence added.
The Ukrainian Navy does not have a significant surface combatant fleet. However, Kyiv has found a way to contest the powerful—at least before the war began—Russian Navy Black Sea Fleet and inflict heavy casualties on it. Taking into consideration this latest action, the Russian Navy has lost over 20 warships, submarines, landing ships, patrol boats, and support vessels, including its flagship, the Moskva guided-missile cruiser.
The Russian Navy was using the B-271 Kolpino to conduct missile attacks on the Ukrainian critical infrastructure and energy grid. Although an attack submarine, which normally packs just torpedoes, the particular vessel was modified to carry Kalibr cruise missiles.
This is the second Russian submarine taken out of action due to Ukrainian attacks. In two separate instances, the Ukrainian forces successfully targeted and struck the Rostov-on-Don, another Kilo-class attack sub, rendering it incapable of further operations.
A Failing Force Protection System
The successive Ukrainian penetrations of the Russian force protection system are a sign of both Kyiv’s impressive capabilities and Moscow’s weak defenses.
“[Ukraine’s maritime suicide drone capability] will highly likely significantly undermine the Russian military leadership’s confidence in Russia’s Black Sea Fleet force protection measures,” the British Ministry of Defence concluded in its latest intelligence estimate.
The Russian military employs a multilayered defense system with air defense batteries, counter-drone nets, and patrol vessels to prevent incidents like the one that took place last week. However, these measures have not prevented the Ukrainian military from launching several suicide drone and missile strikes against Russian vessels and key maritime infrastructure, including the Kerch Bridge that links Russia with the occupied Crimean Peninsula.
About the Author: Stavros Atlamazoglou
Stavros Atlamazoglou is a seasoned defense journalist specializing in special operations and a Hellenic Army veteran (national service with the 575th Marine Battalion and Army HQ). He holds a BA from the Johns Hopkins University and an MA from the Johns Hopkins’ School of Advanced International Studies (SAIS). His work has been featured in Business Insider, Sandboxx, and SOFREP.
Image: Shutterstock.com / Sergei Fokin
