Ukraine using land attack variant of Neptune anti-ship missile

With restrictions imposed on the use of donated weapons against targets outside its borders, Ukraine is developing its own long-range strike weapons, one of which appears to have already been used on Crimea, which is fair game even for systems provided by foreign donors.

On Aug. 23, Kyiv used a modified Neptune anti-ship cruise missile to hit a Russian S-400 air defence system on the westernmost part of the occupied peninsula, a Ukrainian defence official told The War Zone. There are plans, the official added, to eventually strike Moscow and other targets inside Russia - precluded for use by donated weapons - with land attack variants of the Neptune, The Drive reports.

The attack on the S-400 system near the village of Olenivka on Cape Tarkhankut “was 100 per cent carried out by a modified Neptune,” said the official, speaking on condition of anonymity to discuss operational issues.

The official’s statements came just days after Oleksiy Danilov, secretary of Ukraine’s National Security and Defense Council, stated that a new Ukrainian missile hit the S-400. Danilov, however, did not specify exactly what weapon was used. 

The claim also followed one made on August 24 by Yuriy Butusov (@UButusov) who reported that the S-400 strike used an R-360 Neptune anti-ship missile modified for a land attack to strike the S-400. You can read more about that in our story here.

The Russian Defense Ministry (MoD) has released statements over the past two days that seem to corroborate the official’s claim.

The first statement came on August 28, when it claimed on its Telegram channel that a “Ukrainian cruise missile was shot down by on-duty air defence systems over the Black Sea off the coast of the Republic of Crimea.” While it did not name the specific type of Ukrainian cruise missile, that statement is significant because in past claims about shooting down cruise missiles, the Russian MoD has referred specifically to foreign-donated ones. On August 7, for instance, the Russian MoD claimed the shoot down of “nine Storm Shadow long-range cruise missiles” provided by the U.K.

On Tuesday, the Russian MoD claimed for the first time that it shot down a Ukrainian Neptune anti-ship missile. However, it did not say whether it was headed for a ship or land.

The Neptune had previously gained notoriety after two were used to hit the Russian Navy’s Project 1164 Slava class cruiser Moskva in the Black Sea in April 2022. You can read more about that in our story here. The missile had just entered very limited service when the war began, with few on hand for operational applications.

Back in April of this year, the Ukrainian official told us that his country was working on converting the Neptune to a land attack weapon, but that it needed a new guidance system which it did not have at the time. Specifically, certain kinds of chips were needed to complete the system, but that the system was close to completion. On Monday, that official said Ukraine had developed a GPS guidance system that takes the missile to a pre-determined location. The missile's infrared imaging seeker then searches for and locks onto a target based on a pre-loaded image and then makes its terminal attack run on that target. If it cannot match the target, the missile aborts its attack.

This would be a major capability leap as these missiles would not be able to be jammed using electronic warfare and would be very hard to detect during their terminal attack stage due to their seekers being passive in nature. We have discussed the value of the use of imaging matching for targeting, also commonly referred to as DSMAC (Digital Scene Matching Area Correlator) or ATR (Automated Target Recognition) for cruise missiles that are or could be made available to Ukraine.

Currently, Ukraine's donated Storm Shadow and SCALP-EG cruise missiles use this guidance arrangement. Employing it on a reworked Neptune would directly mirror the path that RGM-84 Harpoon took, which turned it into the SLAM (Stand-off Land Attack Missile) missile via modification with infrared passive seeker, among other tweaks. Eventually, the follow-on SLAM-ER would be an even further advance from its Harpoon progenitor. You can read all about these missiles and what they can do for Ukraine here.

It's also worth noting that Russia appears to have employed countermeasures against DSMAC-capable missiles just as Storm Shadow arrived on the scene. From our previous report:

"In fact, Russia may already be reacting to Storm Shadow's automatic target recognition systems, and to the possibility that other Western missiles that use similar arrangements may show up in the future. Independent naval warfare analyst HI Sutton has reported on the new paint jobs that are being applied to the Black Sea Fleet's major surface combatants. Basically, the scheme blacks out the ends of its hull — bow and stern — to change the silhouette of the vessels. While Sutton has stated this is likely to confuse drone boat operators as to what targets they are seeing, we contend that this could also be a countermeasure to ATR-capable missiles, like Storm Shadow, and others that very well may be on the way soon.

Using special paint that reduces IR signature in the wavelengths these seekers work at could potentially confuse their targeting logic. Basically, the imagery it sees would not match that of the targeting imagery/models loaded up into its computer, and thus it would not attack the intended target. How effective such a countermeasure might be is not clear, but Russia invests in other cruise missile countermeasures that are of dubious value."

Since that report, Sutton has stated he believes these paint jobs are also to make it harder to identify particular ships in commercial satellite imagery. We do not believe that is the primary use case, although that could be an added benefit. Further proof may have come just today as imagery of Russia's Engles-2 bomber base 300 miles from the Ukrainian border. The base has come under repeated attack using crude Ukrainian long-range drones. Now, for what seems to be the first time, we are seeing what appears to be a covering on Tu-95 Bear wings that could work to break up the infrared signature of these aircraft in order to confuse cruise missiles with DSMAC/ATR capabilities. This is just one possibility at this time and we may find out the Bear's unusual appearance is due to some other reason, but we have not seen anything similar on these aircraft at the base in recent weeks, with this new feature showing up just yesterday in satellite imagery. The timing is very peculiar and mirrors that the Black Sea Fleet's repaint, as it closely follows the first use of a land-attack capable Neptune missile that supposedly uses infrared for its targeting process.

We must note that it is possible that this Neptune adaptation could use another form of terminal homing or just hit a simple GPS coordinate, but that seems less likely at this time and our source distinctly described its targeting capabilities. This capability would also be important as Russia has capable electronic warfare systems built specifically to counter cruise missiles and localized GPS jamming is very much a real thing that has already impacted the effectiveness of other precision weapons, like M31 rockets fired by HIMARS.

As to why a base so far away would potentially deploy a countermeasure like this, if indeed that is the case? Neptune's reach can be extended and apparently, that is very much in the works.

Fired from the same launcher as the anti-ship variant, the converted Neptune has a range of about 400 km (about 250 miles) and a payload of about 350 kilos (more than 770 pounds), the official told us. If accurate, that would make it the longest-range, hardest-hitting ground attack missile or rocket built by Ukraine. However, we have no way of independently verifying these claims.

While the modified Neptune offers Ukraine its longest strike weapon yet, there are downsides, the Ukrainian defence official said.

One is that the subsonic missile can be thwarted by sophisticated Russian air defence systems. The Russian claim that it shot one down is not improbable, the official told us. But a bigger issue may be how few exist.

“Only a couple of dozen have been produced,” the official said.

On Sunday, Ukrainian President Volodymyr Zelensky told the Ukrainian Ukrinform official news outlet that his country has “significantly increased” the production of Neptune anti-ship missiles.

While it is unclear the delivery timeline for these weapons, Zelensky's assertion is seemingly good news for the Neptune modification program, the official told us.

"I believe the increase, if any, will be in manufacturing the surface-to-surface version."

The U.S., U.K. and France have restricted Ukraine to using their donated weapons only on Ukrainian soil, including Crimea. There are no such preclusions with the modified Neptune or any other Ukrainian-developed weapon.

As a result, even with the currently limited inventory, Moscow will be targeted using the modified Neptune in the not-too-distant future, the official told us. That will add to the discomfort felt in the Russian capital, which has been repeatedly hit by Ukrainian drones.

To reach that roughly 290-mile distance from the Ukrainian border (and perhaps longer from a launch site), the payload will be reduced and the volume of fuel will be boosted. This is a common modification for cruise missile variants.

“That will increase the range and enable it to strike Moscow,” the official said. “It will happen.”

While it may not have the same punch as the weapon that hit the Russian SAM system in Crimea, a successful strike against the right target in Moscow, like a fuel facility, will still be able to impact logistics and have a huge psychological impact on a city that has yet to experience the devastation like that delivered upon Ukraine.

Still, many questions remain. Primarily, how many of these missiles can Ukraine produce and how quickly can they do it. The type's efficacy is also very much in question, regardless of a claimed early success. If Ukraine are getting some help from allies, even in terms of basic expertise, it could help in all of these regards.

Now, like Russia, we will have to wait and see where the land attack Neptune shows up next.