DF-ZF

The DF-ZF is a hypersonic glide vehicle (HGV) developed by the People's Republic of China. It is launched by the DF-17 medium-range ballistic missile. The combined weapon system was likely operational by October 2019.

The United States once referred to the DF-ZF as the WU-14. The DF-17 was previously referred to as the DF-ZF.

Development
According to Ye Youda, a scientist who worked on China's hypersonic weapon project, development was slowed by inadequate computing resources. The weapons project did not have priority access to supercomputers, or it was impractical to use available supercomputers due to their design.

Seven flight tests — with one failure — were conducted from 2014 through 2016; the launches were from the Taiyuan Satellite Launch Center in Shanxi Province, the People's Liberation Army's main long-range missile testing center.

The DF-ZF was likely operational by 1 October 2019, when it made its first official public appearance.

Capabilities
The DF-ZF is thought to reach speeds between Mach 5 (3836 mph) and Mach 10 (7680 mph). The glider could be used for nuclear weapons delivery but could also be used to perform precision-strike conventional missions (for example, next-generation anti-ship ballistic missiles), which could penetrate "the layered air defenses of a U.S. carrier strike group."

Hypersonic glide vehicles are less susceptible to anti-ballistic missile countermeasures than conventional reentry vehicles (RVs). Conventional RVs descend through the atmosphere on a predictable ballistic trajectory. In contrast, a hypersonic glide vehicle such as the DF-ZF can pull-up after reentering the atmosphere and approach its target in a relatively flat glide, lessening the time it can be detected, fired at, or reengaged if an initial attack fails. Gliding makes it more maneuverable and extends its range. Although gliding creates more drag, it flies further than it would on a higher trajectory through space, and is too low to be intercepted by exo-atmospheric kill vehicles. The tradeoff is that warheads have less speed and altitude as they near the target, making them vulnerable to lower-tier interceptors, such as the Mach 17 Russian 53T6, ABM-3 Gazelle. Other potential counter-hypersonic interception measures may involve laser or railgun technologies, but such technologies are not currently available.

A vehicle like the DF-ZF could be fitted to various Chinese ballistic missiles, such as the DF-21 medium-range missile (extending range from 2,000 to 3000 km), and the DF-31 intercontinental ballistic missiles (extending range from 8,000 to 12000 km). Analysts suspect that the DF-ZF will first be used in shorter-range roles as an anti-ship missile and for other tactical purposes to address the problem of hitting a moving target with a ballistic missile. Long-term goals may include deterrence of U.S. missile capabilities.

Since conventional interceptor missiles have difficulty against maneuvering targets traveling faster than Mach 5 (the DF-ZF reenters the atmosphere at Mach 10), a problem exacerbated by decreased detection times, the United States may place more importance on developing directed-energy weapons as a countermeasure. However, after decades of research and development, directed-energy weapons are still very much at the experimental stage and it remains to be seen if or when they will be deployed as practical, high-performance military weapons.

Despite the difficulties that HGVs pose for mid-course ABM interception by systems like SM-3 and GBI, HGVs have yet to overcome substantial obstacles in order to achieve the same success in the terminal phase. For one thing, HGVs can only maneuver drastically in the mid-course phase of their flight path due to extreme pressures during their terminal phase. Additionally, contemporary SAM systems like THAAD, PATRIOT and SM-6 are mostly optimized for terminal phase interception, with the exception of SM-3 and GBI. Furthermore, when HGVs re-enter the atmosphere at hypersonic velocities a plasma sheet will develop which disrupts their communications and sensors. There are two solutions to this. Firstly, HGVs can slow down to supersonic speeds, but this wouldn't make their terminal phase interception any harder than the missiles that current SAMs are designed to intercept. Secondly, HGVs can maintain hypersonic speeds and rely on inertial navigation systems, though this would mean that HGVs can't target maneuvering targets like expensive aircraft carriers, yet these are the exact targets that are valuable enough for HGVs with costs in the tens of millions each, to be worth targeting. These factors have likely contributed to DF-ZF currently being used for a land-attack role only, although an anti-ship variant is in development.