The Neptune Cruise Missile is based on a design of the Soviet anti-ship missile Kh-35, however Ukrainian constructors substantially improved missile range and electronics.
After the 2014 Crimea incident and the complicated activities of the separatist forces in the Donbas region of eastern Ukraine, the Kiev government has been working to strengthen its already decaying defense power. With its dire economic conditions Ukraine cannot build a traditional navy and air force. However, missiles and drones will be more affordable, and will be more effective than warships and manned aircraft.
In 2021 Ukraine is said to have commissioned a battalion of the first domestic RK-360MT Neptune mobile anti-ship missile. However, to confront the Russian army, this small number is not enough. Neptune anti-ship system is equipped with cruise missiles capable of reaching target at distance of up to 300 km. The missile is based on a design of the Soviet anti-ship missile Kh-35, however Ukrainian constructors substantially improved missile range and electronics.

Compared to the Kh-35, the Neptune has a similar design, but has a longer fuselage with more fuel, larger boosters and a number of other modifications. It could be carried and launched from naval, land and air platforms. Development of the Neptun land-based anti-ship missile system was completed in 2019. Ukrainian military trials were completed in 2020.
In 2021 a pre-production system was delivered to Ukrainian military for testing. In 2021 Ukrainian MoD funded production of a batch of Neptun coastal defense systems. It was planned that a batch of 18-19 launcher vehicles will be delivered in 2022. Ukrainian military plans to obtain a total of 54 to 90 Neptun launcher vehicles with missiles.
In terms of performance the Neptun is generally similar to the Russian Kh-35U. It has a planned range of up to 280-300 km. It carries a 145 kg High Explosive Fragmentation (HE-FRAG) warhead, should be efficient against vessels with a displacement of up to 5,000 tons.
Neptun uses an inertial navigation system with active radar in the final stages of flight. Currently Ukraine is facing problems in developing the radar of this type of missile. The missile will fly 10-15 meters above the ground. In the terminal stage, it will descend to 3-10 meters above the surface in order to overcome hostile defense systems.