The pro-Ukrainian milblogger “Colonel GSh” posted images on his Telegram channel on Wednesday that showed the debris from an almost complete Russian Kh-59MK cruise missile that had fallen somewhere over Ukraine during a recent attack. Inspection of the missile showed that two key elements of the missile were missing.
The Kh-59MK (NATO: AS-18 Kazoo) is an upgraded version of the earlier Kh-59 air launched cruise missile. As such it has replaced the solid fuel booster of the earlier model with an internal fuel tank and an external Turbojet. It has also been fitted with an engine mounted below the body just forward of the wings. This has extended the range from 115 kilometers (72 miles) to around 285 kilometers (178 miles).
Missile guidance uses three systems, a mid-course inertial navigation system (INS) twinned with an in-flight command-guidance (CMD-G) update system and a third terminal attack system. The Kh-59-MK has replaced the original TV guidance attack system with the ARGSN U559 active radar homing (ARH) seeker. It carries a 320-kilogram (704 pound) shaped charge warhead (for anti-ship or “bunker-busting” use) or a 285-kilogram (625-pound) cluster munition warhead.
Supposedly, it is designed to be launched from most Russian fighter-bomber aircraft including the MiG-35, Su-30MK, Su-32, Su-35, and Su-24M. It is would fly at speeds of around 1,000 kph (625 mph) at a cruising altitude of 10-15 meters (33– 50 feet) before descending to 4-7 meters (13 -22 feet) during its terminal phase.
However, the missile recently recovered in Ukraine was found to have replaced the ARH warhead with a solid metal block that is used to compensate for the weight of the missing ARGSN seeker, to maintain the designed center of mass of the missile in flight.
It was also found to be using the P95-300 two stage solid propellant engine that was originally produced by Ukraine’s Zaporizhzhia-based Motor Sich plant which was either a relic of Soviet-era stocks or removed from dismantled Kh-55 1970s vintage cruise missile.
The replacement of these two elements indicates a shortage of components to feed the most complex parts of the missile system.
The loss of the ARGSN has the most important operational implications on the use of the weapon. The missile now must rely totally on the INS and the CMD-G update system for guidance. This not only adversely affects its overall accuracy but may increase its vulnerability to some types of countermeasures in the terminal stage of flight. The less powerful engine is also likely to limit its operational range.
This is not the first time Russian missiles have been found to have replaced key components with inferior replacements or inert items simply to balance them in flight. In December 2022 and March 2023 Russian Kh-55SM missiles containing inert, simulated warheads were being encountered in multi-missile attacks probably in an attempt to draw Ukrainian air defense assets away from other “live” missiles.