Ukraine Says It Disabled A Russian Submarine With An Underwater Drone

Ukraine claims it has carried out the first successful combat strike by an underwater drone against a submarine, damaging a Russian Kilo-class boat in the Black Sea port of Novorossiysk and potentially removing a key cruise missile launch platform from the war.

According to a statement published by Ukraine’s Security Service, or SBU, the attack targeted a submarine, using an underwater drone system called Sub Sea Baby. The SBU said the submarine was effectively put out of action. Kyiv estimates the vessel’s value at about $400 million dollars, adding that construction of a similar submarine under current sanctions could cost up to $500 million dollars.

Commentary from the Military Informant Telegram channel, widely regarded as having links to Russian military sources, suggested the unmanned system struck near the submarine’s stern, close to the vertical and aft horizontal rudders and the propeller.

The channel noted that even without a direct hit to the hull, damage to these vulnerable components could sideline the Kalibr-capable submarine for an extended period, adding that “even fleeing to Novorossiysk did not help,” a reference to the Black Sea Fleet’s earlier retreat from occupied Crimea.

According to The War Zone, if the submarine was seriously damaged, Russia would be left with just four Kilo-class boats operating as part of the Black Sea Fleet.

The strike comes amid ongoing peace negotiations, as Ukraine has stepped up increasingly bold operations designed to raise pressure on Moscow. In recent months, Ukrainian forces have struck Russian oil terminals, continued attacks on oil refineries across Russia, and most recently targeted multiple tankers belonging to Russia’s so-called shadow oil fleet.

The SBU said the strike was a joint operation conducted by the 13th Main Directorate of its Military Counterintelligence and the Ukrainian Navy.

Ukraine has previously demonstrated a willingness to attack high-value naval assets in port, striking the Kilo class submarine Rostov on Don twice while it was docked in Crimea, first in September 2023 and again in August 2024. “fter the war we will certainly write a textbook,” Vice Admiral Oleksiy Neizhpapa, Ukraine’s navy chief, told The Economist in July 2023.

Targeted Strikes

The SBU said the submarine carried four launchers for Kalibr cruise missiles, which Russia uses to strike Ukrainian cities. The attack fits a broader Ukrainian directive to strike launch platforms rather than intercept individual weapons.

That approach was also evident in the SBU’s earlier Operation Spiderweb in June, a complex covert campaign aimed at Russian long-range aviation. According to the Wall Street Journal, the operation was conceived after President Volodymyr Zelensky directed the agency to neutralize bombers launching missiles from beyond Ukraine’s air defense range; the operation involved smuggling drones into Russia and launching them from concealed mobile platforms near airfields.

In the months since, analysts estimate that roughly 20% of Russia’s combat ready long-range bomber fleet was rendered inoperable. Surviving aircraft were forced to redeploy to distant bases in Russia’s Far East, adding as much as 10,000 kilometers to individual missions and sharply increasing logistical complexity, operating costs and long-term wear on aging aircraft.

Ukraine’s Tech Navy

Following Russia’s full scale invasion, Ukraine has relied heavily on unmanned systems to offset Russia’s numerical advantage on land and at sea. As The New York Times editorial board wrote, “Inventive Ukrainian forces neutralized the once formidable Russian Black Sea Fleet using small, remote controlled boats loaded with explosives.”

Since 2023, Ukraine has invested increasingly in underwater naval drones. In May 2023, Kyiv unveiled the compact Toloka TK-150 unmanned underwater vehicle at a Brave 1 government defense technology event, signaling where Ukrainian development efforts were heading. As OSINT analyst H.I. Sutton has noted, “The Ukrainian military is secretive about these capabilities, and only reveals what it chooses.”

Ukraine initially employed naval drones to break Russia’s blockade of Ukrainian ports and to strike units of the Russian Black Sea Fleet. Those attacks contributed to the neutralization of roughly a third of Russia’s fleet in the Black Sea. As a result, Russia was eventually forced to withdraw many of its remaining ships from occupied Crimea, relocating them to the port of Novorossiysk on Russia’s mainland.

Serhii Kuzan, chairman of the Ukrainian Security and Cooperation Center told me, “Due to the effective use of drones, Russian naval forces have lost the initiative at sea and have been forced to stay closer to Novorossiysk on the Russian mainland. These successes also enabled the reopening of the grain corridor despite Russia’s withdrawal from the agreement, effectively unblocking maritime trade.”

Ukrainian officials say the cumulative effect of these operations has fundamentally constrained Russia’s naval freedom of action in the Black Sea. Kyrylo Budanov, head of Ukraine’s military intelligence, has said Ukraine has effectively locked the Russian Black Sea Fleet at its permanent base in Novorossiysk.

According to Budanov, Russian combat vessels now rarely sail beyond Novorossiysk, leaving port primarily to launch missile strikes before returning quickly to base.

Kyiv has also leveraged its growing naval drone capability to strike high value infrastructure targets, including the Kerch Bridge linking Russia to occupied Crimea. Analysts have speculated that a June attack on the bridge may have involved Ukraine’s Marichka underwater drone, a six meter long multipurpose strike platform reported to have a range of up to 1,000 kilometers.

By early 2023, Sevastopol harbor was protected by as many as six layers of nets and boom defenses aimed specifically at blocking Ukrainian naval drones. The expanded defenses suggest the Kremlin has been forced to extend anti-drone coverage across occupied Crimea, both to protect the Kerch Bridge and to shield remaining naval assets relocated to Novorossiysk.

Dmitry Gorenburg, a researcher with the Center for Naval Analyses, told me, “Prior to the war, Russia was seen as the controlling maritime power in the Black Sea. This is no longer the case, and sea control is now contested and will remain so for the foreseeable future.”

For Kyiv, each innovation has been guided by cost asymmetry. “Maritime drones are relatively sophisticated yet inexpensive to produce, with costs ranging from $250,000 to $300,000 per unit,” said Kuzan.

“It is worth noting that even before the full-scale invasion, Ukraine understood that achieving military parity with Russia was impossible,” Kuzan added. “As a result, the navy had to be built according to an asymmetric principle.”

An Ongoing Adaptation Cycle

As Ukraine continued to strike Russian ships and deploy drone carriers to extend operational range, Moscow was forced into repeated adaptation, constantly trying to figure out how to defend itself from Ukrainian unmanned systems.

According to “Xen,” a former U.S. special forces operator, who has worked with a Ukrainian Special Operations Forces regiment, the adaptation cycle now typically runs six weeks to six months, including for Ukrainian naval drones: a new tactic creates disruption, countermeasures follow, and are then met by rapid counters of their own. The result is a sustained cat-and-mouse dynamic that permanently alters tactics, techniques, and procedures once used with relative impunity.

Earlier analysis from the Center for Maritime Strategy suggested that Ukraine’s maritime campaign would aim first to force Russian naval assets out of Crimea and then to constrain their operations elsewhere in the Black Sea. That shift has now largely occurred.

With much of the fleet now confined to Novorossiysk, Ukrainian forces are probing for weaknesses and striking launch platforms directly, exploiting basing constraints to reduce Russia’s ability to bombard Ukrainian cities. The Kremlin will inevitably seek new countermeasures, while Kyiv moves to sustain the adaptation cycle that has kept Russian naval operations under constant pressure.