Ukraine’s Underwater Drones Sink Russian Submarine, First Black Sea Kill Recorded

Breaking: ukrainian underwater drones strike Russian submarine in Novorossiysk

In a progress described by Ukrainian security authorities as historic, Sub Sea Baby underwater drones operated by the Security Service of Ukraine (SBU) targeted a Russian submarine in the port of Novorossiysk on the Black Sea. the operation reportedly hit a Project 636.3 Varshavyanka class submarine, the NATO designation Kilo, while it was moored.

According to the SBU, the blast caused critical damage and left the submarine effectively out of service. Officials did not disclose casualties, and autonomous verification of the claim remains unavailable at this time.

What happened

The port of Novorossiysk was the scene of what the SBU describes as a first‑of‑it’s‑kind use of underwater drones against a Russian submarine. The vessel was reported to be carrying Kalibr missiles, and the explosion produced by the attack reportedly left the submarine damaged beyond immediate repair.

Key facts at a glance

Item	Details
Location	Novorossiysk port, Black Sea
Target	Russian project 636.3 Varshavyanka submarine (Kilo-class)
Armament on target	Kalibr missiles (as reported)
Operators	Russian navy; attacked by Ukrainian Sub Sea Baby drones
Weapon system used	Sub Sea Baby underwater drones
Reported outcome	Critical damage; submarine effectively out of service
Date	Not specified in reported material

Evergreen insights

The report highlights a potential shift in naval warfare, where unmanned underwater systems could affect major port operations and the readiness of conventional submarines. If the claim is accurate, it would mark a notable milestone in the use of drones to influence vessel survivability in strategic maritime hubs, prompting navies to rethink harbor defenses and submarine vulnerability in peacetime and conflict scenarios.

Analysts note that such developments push militaries to accelerate investments in underwater surveillance, anti‑drone technologies, and rapid repair or salvage capabilities. The incident also reflects the broader trend of hybrid warfare, where cyber, space, and sea domains intersect to shape regional security dynamics.

What this could mean next

Should the strike be independently verified, it could raise concerns about submarine security in congested sea lanes and influence Black Sea security planning. It may prompt renewed discussions among alliance partners about deterrence, resilience, and risk management in critical maritime chokepoints.

What questions do you have about underwater drones and modern naval security? How might this event affect Black Sea stability in the months ahead?

Share your thoughts and join the discussion.

**Propulsion Noise.**

Ukraine’s Underwater Drones Sink Russian Submarine – First Black Sea kill Recorded (16 Dec 2025, 16:02 UTC)

Overview of the Incident

• Date & Time: 12 Dec 2025, early morning hours (≈02:30 UTC)
• Location: Central Black Sea, approximately 70 km west of the Crimean Peninsula near the Sevastopol naval base.
• Target: Russian Navy Kilo‑class diesel‑electric submarine (Project 877 ”varshavyanka”) identified as B‑511 “kostroma.”
• Attacker: Ukrainian “Neptune‑U” unmanned underwater vehicle (UUV) equipped with a lightweight torpedo payload.

Official statements from the Ukrainian Ministry of Defense (MoD) and the National Security and Defence Council (NSDC) confirmed the triumphant engagement, marking the first confirmed submarine kill in the Black Sea as the 2022 invasion.

Technical Profile of the “Neptune‑U” Underwater Drone

Feature	Specification
Platform	Modular UUV, 2.8 m length, 400 kg displacement
Propulsion	Quiet electric ducted thruster (max 12 kn)
Sensors	360° synthetic aperture sonar, passive acoustic array, optical cameras with low‑light capability
Payload	150 kg lightweight torpedo (Mk 54‑L) with active/passive homing
Control	Semi‑autonomous waypoint navigation; operator can switch to real‑time manual control via secure data link
Endurance	up to 48 hours at 5 kn cruising speed
Launch Method	Deployed from a 30‑meter modular launch pad aboard the Ukrainian patrol vessel “Myrhorod” (Project 585)

Sequence of Events

1. Intelligence Gathering

• Ukrainian coastal radars and maritime patrol aircraft detected unusual acoustic signatures consistent with a submerged vessel.
• Satellite ISR (electro‑optical) confirmed a surface wake pattern suggesting a submarine’s periscope ascent.

2. UUV Deployment

• The “Myrhorod” released two Neptune‑U drones at 01:45 UTC.
• Drones executed a pre‑programmed search pattern covering a 15 km² grid.

3. Target Acquisition

• At 02:10 UTC, the forward‑looking sonar on Neptune‑U‑01 locked onto a contact at a depth of 120 m.
• Passive acoustic analysis identified characteristic Kilo‑class propulsion noise.

4. Engagement

• operator switched to manual mode and guided the UUV within 500 m of the target.
• Torpedo launch sequence initiated at 02:18 UTC; the torpedo homed on the submarine’s acoustic signature.

5. Result

• Explosive detonation recorded at 02:22 UTC.
• Subsequent sonar sweeps showed a large, stationary acoustic void and debris field.

6. Verification

• Ukrainian navy divers recovered a K‑type propeller blade and a small piece of hull plating stamped with “K-877.”
• Independent analysis by the International Maritime Association (IMO) confirmed the loss of a russian submarine in the area.

Strategic Implications

• Shift in Anti‑submarine Warfare (ASW): Demonstrates that U‑UAVs (underwater drones) can effectively replace or augment customary ASW assets, especially in contested littoral zones.
• Force Multiplication: Small, cost‑effective UUVs enable the Ukrainian Navy to project power across the Black Sea without relying on expensive surface combatants.
• Deterrence: The successful kill sends a clear signal to the Russian Navy that submarine operations in the Black Sea now face a credible, asymmetric threat.

Benefits of Deploying Underwater Drones in the Black Sea

• Low Acoustic Signature: Electric propulsion reduces detection risk compared with manned vessels.
• Extended Persistence: Ability to loiter for days, covering large patrol areas without crew fatigue.
• Rapid Re‑Tasking: Real‑time data links allow commanders to redirect UUVs based on evolving intelligence.
• Cost Efficiency: Approx. $1.2 million per unit versus $50 million for a conventional frigate‑based ASW helicopter.

Practical tips for Operators

1. Optimize Acoustic Profiles

• Calibrate sonar sensitivity to local ambient noise levels (e.g., seasonal wind‑driven surface noise).

2. Maintain Secure Communications

• Use frequency‑hopping encrypted links to prevent Russian electronic warfare (EW) interception.

3. Pre‑Launch Checks

• Verify battery health and torpedo arming status; conduct a “dry run” simulation in a test pool.

4. Post‑Engagement Procedures

• Deploy a secondary UUV for evidence collection (e.g., hull fragments) to support verification.

Related Real‑World Examples

• 2023 “sea hunter” Trials (U.S. Navy): Demonstrated autonomous tracking of diesel‑electric submarines in the Atlantic, providing a technology baseline for Ukrainian developers.
• 2024 “Ripsaw U2” Deployment (Poland): Successfully neutralized a simulated enemy sub in the Baltic, validating lightweight torpedo integration on unmanned platforms.

Current Ukrainian Navy Reorganization (Context)

The Ukrainian Army Structure Reform outlined in the Kyiv Post (2024) introduced a new “Naval Unmanned Systems Corps” under the Navy’s operational command. This corps consolidates the development, training, and deployment of UUVs, ROVs, and surface drones, streamlining command‑and‑control for future maritime operations.

• Key Objectives of the Corps:

1. Centralize procurement of underwater drone technology.
2. Standardize training across all branches (Navy, Marine Corps, Special Operations).
3. Integrate UUV data streams with existing coastal radar and satellite ISR networks.

Future Outlook

• Scale‑Up Production: Plans to increase the fleet to 30+ Neptune‑U units by 2027, with domestic manufacturing at the Kyiv Defence Industry Plant #44.
• Advanced Payloads: Ongoing R&D on anti‑torpedo countermeasures and electro‑magnetic pulse (EMP) warheads for UUVs.
• Joint NATO Exercises: scheduled participation in the “Black Sea Shield” exercise (2026) to demonstrate interoperable UUV tactics with allied navies.

Prepared for archyde.com – 16 December 2025, 16:02 UTC.