Ukrainian Navy strikes Slava class cruiser Moskva

On the evening of April 13 the Slava class cruiser Moskva, flagship of the Black Sea Fleet, was reportedly struck by Ukrainian Neptune anti-ship missiles. The details the attacks are unavailable to obtain through OSINT and in the 24 hours following the attack several pieces of information and speculation have come to attention that allows us to piece together the broad lines of the attack and its aftermath.

The Slava class cruiser Moskva operated in the vicinity of Snake Island. This area has been her standard area of operations since the beginning of the Russian invasion of Ukraine. From this position, the vessel is able to dominate the maritime approaches towards the Ukrainian coast, most notably towards Odessa. The cruiser is also equipped with a battery of 64 S-300F surface to air missiles, allowing it to set up an zone in which Ukrainian aircraft are at risk of operating.

It is unknown if the cruiser was operating on its own or if she was near other vessels that acted as an escort. From what has been reported through OSINT it appears that the cruiser was the sole warship in this area though this can not be assessed with certainty.

The Ukrainian side claims that it operated a Bayraktar drone and that it launched two Neptune anti-ship missiles towards the cruiser.  The launch site reported as somewhere between Odessa and Mykolaiv which is a distance of over 100 kilometers. The drone was allegedly used to distract the crew of the cruiser so that they would not notice the two cruise missiles approaching the vessel. This statement is most likely false as it paints a too simple picture of the attack. Taken in account how warships operate, how weapons systems work and how weather also impacted the sensors of the cruiser we can deduct with a reasonable margin of certainty how the attack took place.

Detection and initial launch phase

Knowing that the Moskva operates near Snake Island, scouting for and detecting the cruiser is relatively easy as her area of operations is known. A Bayraktar drone most likely scanned the area, detected the Moskva and passed its location along to the Neptune missile battery which fired two Neptune missiles. The Neptune missile has an active seeker which can be detected by the Moskva but with her position, speed and heading known, both missiles could be launched to a waypoint close to the cruiser. Once at this waypoint, the missiles would go active, minimizing the time their active seekers could be detected. This would have decreased the reaction time available to the Russian crew.

It is most likely that the Russian Navy detected the drone operating near them but the question is why it was not engaged and allowed to operate freely. It is possible that the crew of the Moskva was struggling to keep track of the drone and allow for an accurate firing solution. We have seen in the past that the Bayraktar drone holds an advantage over Russian air defense systems such as the Tor and the Buk but also over the Pantsir which is specifically designed to counter unmanned aerial vehicles. There is no reason to assume that the sensors on board of the Moskva would be better then those of the ground based air defense systems of which the Bayraktar has demonstrated to be able to overcome.

The Moskva operates two radar systems, the most potent being the dome shaped 3R41 Volna fire control radar. This radar is used to track the targets and provide the most accurate target data available for the S-300 missiles to act upon. This radar reportedly has one major weakness, namely that it only has a 180 degree field of view. This leaves the other side of the battlefield unguarded. The Bayraktar drone could indeed have acted as a distraction by having the 3R41 Volna fire control radar pointed away from the direction from which the Neptune missiles were comming.

Impact of the weather during final approach

The top mounted MR-800 Voskhod air radar provides a 360 degree picture of the airspace around the cruiser. The radar is however specifically designed to keep track of aircraft and is less suited for cruise missiles that fly at low altitudes such as the Neptune. By flying between three to ten meters in its final phase, the Neptune tries to stay underneath the radar coverage for as long as possible, thereby further decreasing the reaction time available.

At this point weather conditions start playing a role as well. The weather that evening was relatively bad with rain being reported and a windspeed of 13 kilometers/hour. With the wind a three Beaufort the sea would be in Sea State 3 with waves being between 0.5 and 1.25 meters in height. These conditions create clutter on the radar screen as radar waves are being randomly reflected from wave tops and rain showers. This clutter is most dense close to the vessel, making detection of nearby objects by radar difficult to impossible. The use of radar during the evening and night is significantly higher as visual observation becomes less possible.

Example of clutter on a radar screen. Nearby wavetops are reported almost as intense as the vessel further to the east. Vessels close by could even be rendered invisible in this clutter.

Clutter on radar screens can be diminished by decreasing the sensitivity of the radar. This results in clutter being ignored and only larger objects such as vessels and islands still being detected. By decreasing the sensitivity it is also no longer possible to detect objects over long distances as their weak return signals are no longer processed.

We do not know at what settings the Russian radars were turned to but given the bad weather and night time conditions it is not unlikely that the sensitivity was somewhat decreased to allow for a clearer view on the radar screens. This statement is however speculation until verified by the Russian crew themselves.

Impact and initial damage

It is unknown to us at what point the Neptune missiles were detected an by which means, being actively on radar of passively by ESM detection. Depending at the range at which they were detected, response time is low, at best two to three minutes. During this time the missile needs to be detected, tracked with certainty to allow for a firing solution. This solution in turn needs to be transferred to the air defenses to allow for a successful interception. If the crew of the Slava were indeed already struggling to track the Bayraktar drone and unable to engage it, chances are that they were less observant to the incoming missiles and slow to react to this new threat. Once again, without inside verification this remains speculation. For the same reason, it unclear if the cruiser was able to launch missiles in self defense or active its close in weapon systems in time.

One could argue that the Bayraktar drone should have been able to film the attack but for this the drone would need to be close to the cruiser and would have most likely resulted in the Russian crew being able to engage it successfully.

It is unclear if both missiles struck the Moskva. Russian media do admit that a fire broke out on board of the vessel which eventually reached the ammunition on board and causing it to explode. Once again, with Russia downplaying the event for propaganda reasons, it is hard to tell what really happened. But even in this version at least one missile must have struck the cruiser to allow for the fire to begin with.

OSINT reports during the first 24 hours range wildly with reports that one missile caused fire that reached the ammunition magazines and caused further explosions. On the other end are claims that both missiles struck the vessel, causing explosions on board with the subsequent damage being too much and the vessel rolling over and sinking. All we can say with certainty, since it was admitted by Russian media, was that fires and explosions took place on board.

Damage control and aftermath

We can not be certain where the missile, or missiles for that matter, struck the cruiser. They most likely hit the vessel where the radar signature was biggest, either on the forward or aft superstructures. These areas are indeed dangerously close to the P-1000 Vulcan anti-ship missiles mounted on the forwards half or the S-300F magazines halfway aft. Even if the Neptune missiles failed to hit and explode these weapons systems, fires in these areas have the potential to cook and set off these missiles rather quickly if being uncontrolled.

The crew most likely will put up an effort to save the vessel and control the fires and damage. Without the knowledge of where the Neptune struck the Moskva, the damage inflicted remains impossible to deduce.

At some point however the crew decided to abandon ship, or as the Russian media states it; evacuate. The true reasons for this evacuation remains unknown to the OSINT community at this moment but most likely the reason was that the damage and fires raging were to big to handle for the crew and the assessment was made that the vessel was no longer salvageable.

On the other end of this story are claims that the fires were put out but the vessel was rendered inoperable and as such it was safer for the crew to abandon the vessel and await the arrival of other vessels. Given maritime mindset of saving the vessel at all costs, it is most likely that the cruiser was abandoned due to the inability to save it.

The cruiser however did not sink, unlike many claims in the hours following the attack. Russian media claim that the vessel was under tow during the morning and returning to base. This statement seems to be backed up by Sentinel-1 SAR satellite imagery of what appears to be the cruiser with three smaller vessels nearby.

The fact that the cruiser is under tow means that she has lost propulsion and steering. Given that these systems are located inside the vessel, most of it underneath the water line, suggest that there is massive internal damage, most likely to fires and explosions. Even if the bridge had been knocked out of action, local steering and operating the machinery in the engine rooms would allow for some control over the vessels movements.

Final assessment of the attack will only be possible once there is visual confirmation of the Moskva in order to determine the damage sustained and how likely she can return to service. For this matter it is most likely that the Moskva will be towed into Sevastopol during the night to prevent photos to be taken. Attempts will also be made to have it docked in a remote location that is visually difficulty to observe but it will be impossible to hide her from satellite imagery.. Even if the cruiser sustained limited damage, with propulsion and steering being taken out, extensive fire damage and explosions taking place, the damage will be significant and put the cruiser out off action for several weeks if not months.