On December 15^th, the Security Service of Ukraine (SBU) reported that it had struck an Improved Kilo-class submarine at the Russian naval base at Novorossiysk. The attack was reportedly a joint operation between the 13th Main Directorate of Military Counterintelligence of the SBU and the Ukrainian Naval Forces and made use of a “Sub Sea Baby” drone.

The SBU also released a video of the attack (see below) showing how the drone struck the stern of an Improved Kilo-class submarine moored at the far end of the submarine pen inside the naval base. So far there is no independent verification if the submarine was sunk in port. Available images of the attack shows a massive explosion at the stern of the submarine, likely resulting in significant damage to the hull, propulsion as well as the aft vertical and horizontal dive planes. Even if the submarine doesn’t sink, the possible damage suffered will be extensive enough to render the submarine inoperable for a serious period of time. The Russian Ministry of Defense however claimed that the attack failed and that no vessel inside the naval base was damaged.

Sub Sea Baby – Ukraine’s newest weapon

Ukraine reportedly used a new type of unmanned maritime drone called the “Sub Sea Baby” drone. The drone is an Unmanned Underwater Vehicle or UUV, capable of remaining submerged during the attack run and is most likely a further development from the Ukrainian Sea Baby Unmanned Surface Vehicles (USVs) that have been proven to be highly successful in attacking Russian surface ships.

This weapon probably functions as a type of autonomous torpedo. If so, it probably can be guided towards the general vicinity of it targets via waypoints before its own systems take over and steer the weapon autonomously to its target. This could explain how the Sub Sea Baby was able to navigate inside the naval base and towards the submarine pen, a route that requires several turns in confined spaces.

It is unclear if the weapon operates independently once launched or if some form of real-time guidance is still possible. Ukraine’s SBU released a video of the attack which appears to originate from a harbor camera, suggesting that Ukrainian intelligence services were able to hack these camera’s to monitor Russian naval activity within the naval base. The released images show the warships inside the harbor being labeled in green boxes, suggesting that the images are probably analyzed by some form of AI to help identify the types of warships present inside the harbor. It is unknown if such imagery was used to guide the Sub Sea Baby drone in real-time.

Maritime war in Black Sea continues to escalate

The Ukrainian attack against the naval base at Novorossiysk takes place in a period of renewed escalating maritime warfare in the Black Sea. The region has been relatively quiet in recent months with attacks largely limited to UAV strikes against Crimea and Novorossiysk. These UAV attacks against Novorossiysk mainly struck energy related infrastructure such as the oil terminals inside the harbor.

Recently, the Ukrainians have started to intensify their maritime operations in the Black Sea by attacking several vessels of Russia’s Shadow Fleet underway to Novorossiysk to load oil. The first attacks struck the tankers Virat and Kiaros on November 28^th, followed by Sea Baby drones striking the tanker Dashan on December 10. In all three cases, Sea Baby USVs were able to disable the tankers, preventing them from continuing their voyage to Novorossiysk and disrupted Russia’s oil smuggling activities.

Russia responded however by targeting commercial vessels inside the port of Odessa with Geran-II drones and cruise missiles

On Friday December 12^th, at 16:00 local time, the Russians struck the Turkish car ferry Cenk T at the Chornomorsk port at Odessa. According to Cenk Denizcilik, the Turkish company that owns the cargo ship, the Cenk T was carrying food supplies when it was struck. Two other vessels, also linked to Turkey and carrying food supplies, were allegedly damaged as well during follow up strikes later in Friday.

It is probable that Ukraine is now stepping up its attacks against Russia’s Black Sea Fleet in retaliation for the drone and missile strikes against Odessa. According to the SBU, the Improved Kilo-class submarine  that was struck was reportedly equipped with 4 Kalibr cruise missiles. These missiles are used by Russia to strike strategic infrastructure such as ports and power grids in Ukraine. We do not known if the submarine in question was preparing to strike Ukrainian targets in the near future. Improved Kilo-class submarines allegedly have a standard load of 4 to 6 Kalbr cruise missiles in their torpedo room.

It might also be possible that Ukraine was acting pre-emptive. Russia’s Black Sea Fleet, though severely weakened from drone and missile strikes during a maritime campaign in 2022-2023 is on paper still capable of blockading the Ukrainian coast and interdicting civilian traffic heading to and from Odessa.

Improved Kilo-class submarines would be less suited for such a task as they operate under water and are thus unable to hail ships. They are however prime weapons to be used to enforce a hard blockade with Russian ships opening fire at civilian vessels entering a blockaded zone.

 

Ukraine’s latest maritime strike holds larger implications

The Ukrainian Sub Sea Baby drone was able to bypass the existing harbor protection systems in place at the naval base of Novorossiysk.  Over the past years, Russia has been working to provide protection for its vessels inside the naval base with the presence of floating pontoons to block the naval base entrance. These systems were however deployed against the threat posed by Ukrainian USVs and are less suited to be used against UUVs.

For the moment, the Russian naval base at Novorossiysk remains vulnerable for additional follow up strikes with the Sub Sea Baby drone until Russia has deployed additional protection systems that deal with the new UUV threat. With the naval base at the moment no longer being a safe location for the Black Sea Fleet, it remains to be seen how the Russian fleet will respond. There are options to move the warships even further away from Ukraine by basing ships in Sochi and Poti in Abkhazia. None of these harbors however have the necessary infrastructure to sustain the warships in their operations, thus rendering the Black Sea Fleet largely combat ineffective.

With Ukrainian UUVs now able to bypass existing defense systems at Novorossiysk, all eyes are now on the Kerch Bridge and the possibility of renewed Ukrainian attacks against the bridge. The Kerch Bridge has been struck several times in the past. An earlier attack on June 3^rd used underwater explosives planted by the SBU and with an equivalent to 1,100kg of TNT, to destroy the underwater support structures of the Kerch Bridge. All these attacks have so far been unable to destroy the bridge though the damage that was inflicted was sufficient to halt traffic for a limited amount of time and pose restrictions to the amount of trains and their cargo passing the bridge.

Ukraine’s goal is to destroy the Kerch Bridge, cutting Crimea off from the Russian mainland and instigate a blockade of the Crimea peninsula in the hopes of making the Russian positions on the peninsula untenable. Sub Sea Baby drones could in theory allow the Ukrainians to bypass the defenses put in place to protect the bridge against maritime attacks as these defenses are deployed with USV attacks in mind. However, it is doubtful if a Sub Sea Baby drone is able to damage the pillars of the bridge to such an extent that it can be brought down.

By disabling an Improved Kilo-class submarine, the Ukrainians further reduced Russia’s submarine strength in the Black Sea to just two operational submarines out of the original six. Two Improved Kilo-class submarines were located in the Mediterranean at the start of the conflict and remained outside the Black Sea to this day. A third submarine, the Rostov-on-Don, was destroyed on September 13, 2023, by Storm Shadow missiles while located in a drydock in Sevastopol. The Improved Kilo-class has been one of Russia’s main weapons for power projection in the Mediterranean over the past years together with Kalibr equipped surface warships. Destroying these submarines will further limit Russia’s capabilities to project power in the Mediterranean after the war in Ukraine ends.