Chinese media have announced the seventh successful test of a hypersonic glide vehicle (HGV). The missile was fired from Wuhzai in Shannxi province and landed in the west of the country. Referred to as the DF-ZF, the projectile is reportedly capable of reaching speeds of up to 12,000 kilometers an hour.
Standard ballistic missiles have a relatively predictable trajectory. The missiles booster sections (A,B) lift it into the upper atmosphere until it hits it maximum height (5). As it ascends, the missile’s sections break off as they burn through their fuel (3,4). Eventually the finally stage of the missile drops off, leaving the reentry vehicles (D) to complete the journey. The reentry vehicles tip over and descend back toward the planet, pulled by gravity (7,8).
The HGV concept involves loading a ballistic missile with an aerodynamically maneuverable reentry vehicle instead of a ballistic one. After reentry, instead of simply falling toward the target, the HGV pulls up and glides toward the target on a flat trajectory at hypersonic speed. The vehicle skims through the stratosphere, flying too low for exo-atmospheric interceptors. When it reaches the target area the vehicle dives on ir’s objective, striking it at several times the speed of sound.
The primary advantage of weapons like the DF-ZF is survivability. Modern missile defense systems shoot down missiles by predicting their trajectories and firing interceptors where the reentry vehicle is calculated to be by the time the interceptor crosses it’s path. After the interceptor comes close to the target area, a seeker in the interceptor’s nose does the more precise work of guiding the interceptor towards the actual reentry vehicle. The interceptor then either strikes or, explodes near, the warhead, destroying the reentry vehicle.
This method is only effective on ballistic missiles with predictable trajectories. The HGV concept is designed to beat these systems by maneuvering in the air after the boost phase. Once the vehicle breaks from it’s ballistic trajectory, the calculation made by the air defense system becomes useless. Without correction, the interceptor will fly into empty space instead of into the missile’s path.
A weapon like the DF-ZF could threaten U.S naval assets operating near China’s shores as part of China’s A2/AD strategy. Currently, aircraft carriers and Aegis destroyers do not have countermeasures to defeat a missile like this. Basing such missiles on the Chinese coast or a few artificial islands like Woody or Fiery Cross Reef would create a A2/AD zone that could virtually lock down the area between the Chinese mainland and the First Island Chain.
While the DF-ZF is a serious threat, the system has some limitations. American warships are moving targets that can operate from beyond the range of Chinese radars. There is currently no evidence that China deploys an over-the-horizon radar with a range of any more than 300 km. Their current mainland radar installation was designed in 1967 and their newer installation in the South China Sea has a similar range.
As soon as a carrier leaves the South or East China Sea the surrounding Islands will block the radar signal. Even in open ocean, at 300 km from the Chinese shoreline the American ship will become undetectable due the the radar’s range limits.
China could get around this limitation, but it would fairly complicated. One option would be for Chinese assets to penetrate American defenses, loitering and tracking warships while the missiles are launched. The system would require an advanced electric communications and data link capabilities.
It would also necessitate aircraft or ships stealthy enough to sneak around acarrier battle group without being detected. China will not have assets like this in service for at least a few more years.
Initially the missile itself is unlikely to benefit much from high powered radars anyway. Based on airspace restrictions during the test, the range of the test was probably around 1200 km. Initial use with shorter range missiles is therefore likely. Factoring in the extended range provided by the glide technique, the test vehicle was likely mounted to a DF-16 missile, which normally has a range of about 800 km.
While this is the current state of China’s DF-ZF program, a longer range version is likely not far behind. A DF-21 or DF-26 with a DF-ZF type warhead could be used to strike fixed targets across the region. A HGV aimed at a U.S base like Guam or Yokosuka would be capable of penetrating current air defenses and striking assets like runways, control towers, docks, or even the U.S naval magazine.
These missiles would be capable of destroying most targets with their kinetic energy alone, but there is a concern that China will eventually nuclearize the weapon, creating a nuclear missile that can’t be shot down. This weapon could threaten all U.S assets in East Asia. Another fear that such a weapon could be paired with an ICBM like the DF-31 which would allow it to strike targets in the United States, strengthening the Chinese nuclear deterrent and setting off an arms race.