To Strike the S-400 In Crimea, Ukraine Tweaked Its Neptune Missile

The Ukrainian navy reportedly used some of its Neptune anti-ship missiles in the missiles’ secondary land-attack mode to blow up a Russian air force S-400 air-defense battery in western Crimea on Wednesday.

That the one-ton Neptune can strike targets on the ground should come as no surprise. Ukraine’s Luch Design Bureau modeled the Neptune on the Russian Kh-35, itself an answer to the American Harpoon anti-ship missile, which also has a land-attack mode.

The Russian air force deployed the S-400 battery to Cape Tarkhankut in Crimea in 2016, two years after Russian forces invaded the strategic peninsula. The S-400 and its attached Podlet K1 radar could detect and strike aircraft and missiles 200 miles away, allowing it to control the entire western Black Sea as far west as the port of Odesa in southern Ukraine.

The S-400, the Podlet radar and other weapons on the Crimean cape—including a battery of Bastion anti-ship missiles—topped the list of prospective targets as Ukraine expanded its deep-strike capability this year.

To extend the range at which its forces can attack Russia’s forces, Ukraine has acquired American-made Harpoon ground-launched anti-ship missiles plus Western-made air-launched cruise missiles: British Storm Shadows and French SCALPs.

At the same time, Ukraine has developed its own deep-strike munitions, including S-200 ground-launched air-defense missiles that the Ukrainian air force modified into land-attack weapons. The Ukrainian navy made similar modifications to its Neptune ground-launched anti-ship missiles, which most famously holed and sank the Russian navy cruiser Moskva in April 2022.

The low-flying, subsonic Neptune lends itself to the land-attack role, just like its predecessor missiles—the Kh-35 and Harpoon—do. To give the first-generation, anti-ship-only Harpoon a land-attack mode in its Block II model in the late 1990s, American missile-maker Boeing added GPS-aided inertial navigation, complementing the original Harpoon’s radar seeker.

A radar seeker alone is enough for striking ships, as a ship reflects a clear radar signature relative to the flat water around it. Ground targets, by contrast, are surrounded by the clutter of buildings, trees and uneven terrain. But juice a radar-guided missile with GPS, and you might get enough discrimination to steer the munition through the clutter.

Luch in its wisdom fitted the Neptune with GPS from the start. But the design bureau recently made additional tweaks to the missile’s seeker to optimize its land-attack mode, a Ukrainian official told The War Zone this spring. “Once we get that, the Neptunes can hit targets [225 miles] away,” the official said. “We are pretty close.”

With a 225-mile range, a Neptune battery could fire from the relative safety of Odesa and strike Russian forces across most of Crimea. The Wednesday strike on the S-400 battery might be the first time Ukraine has used the modified Neptune in anger. Russian air force officials surely are asking themselves why the S-400—their best air-defense system—failed to intercept the very Neptunes that destroyed it.

The S-400 raid probably won’t be the last for the upgraded Neptune. While the exiled Ukrainian mayor of Russian-occupied Mariupol claimed the Wednesday strike destroyed a Russian Bastion anti-ship missile battery, it’s becoming clear the Bastion escaped damage. But it might be next on the list of targets as the Ukrainians escalate their attacks on Russian forces in Crimea.