What are Hypersonic Weapons?

In 2018, President Putin delivered a speech during state-of-nation address announcing the adoption of upcoming hypersonic weapons into Russian military. Later in the year, China has showcased their own weapon during the military parade. In 2020, the US President boasted about ’super-duper’ missile in the making. World leaders are talking about the emerging weaponry because of their ability to affect international security in the sphere of theatre of conflict and even in the strategic realm. Hypersonic weapons are the emerging military technology and great powers are trying to incorporate them in their arsenals However, for those implications to be understood, the very idea of hypersonic weaponry has to be comprehended. In this short piece, I will briefly go through hypersonic speed, outline what hypersonic weapons are, show how they are different from previous types of weapons and show examples of created and prospective weapons.

Hypersonic speed is considered to be the speed above Mach 5 (6125 km/h or 3806 mph). When things are moving this fast, the air around them changes significantly and designing objects for such a fast flight is much more complicated. For comparison, passenger jets move at roughly 700-950 km/h, while the fastest fighter jet/interceptor in service with significant numbers, MIG-31 can achieve speed of Mach 2.8.[1] It is true that Mach 5 is exceptionally fast, but there are many man-made objects moving far faster outside of the atmosphere, in space, like most probes, satellites and space shuttles. However, those are not moving in the atmosphere where atmospheric drag significantly affects the flight pattern. Very few man-made objects have attained those speeds in atmosphere. One example is experimental rocket plane North American X-15 .

Hypersonic weapons are manoeuvrable weapons that are moving at hypersonic speed. All Intercontinental Ballistic Missiles are hypersonic since they move at speeds above Mach 5 during re-entry, with some surpassing even Mach 20. Many lower ranged ballistic missiles can also attain hypersonic speed. Still, the trajectory of their flight is parabolic as they fly up and then ultimately fall down to earth. There have been some limited changes to parabolic trajectory in the atmospheric part of the flight with the adoption of the MARV warheads, although these are only part of the last moments of the warhead’s flight. Hypersonic weapons, by comparison, are staying in hypersonic speed during most of their flight, which is conducted in the atmosphere, while being capable of manoeuvring during the entire flight. This has been an exceptional technological challenge for decades as making materials that can be used as rudders for manoeuvring at such speeds is extremely difficult. Also, making scramjet engines capable of sustaining such speed for extended periods of time has been a great challenge as well. Nevertheless, mastering technological challenges has its benefits.

This manoeuvring at such great seed is very significant since it makes missiles very hard to be intercepted. Subsonic and supersonic missiles are not easy to be intercepted either. We have seen from recent airstrikes in Syria how difficult it is to intercept large scale attack of subsonic missiles. According to wargaming, chances for AEGIS ships, the most advanced missile defence ships in the world, to stop Mach 4 Kh-32 anti-ship missiles are poor, with large scale salvo attack having nearly guaranteed hits. Technology is improving rapidly, and there are many ongoing modernizations regarding quality and quantity of anti-missile systems like the AEGIS and the S-400, with more layers of defence being added such as ESSM, Pantsir and S-350. While high-value assets are not safe even with the most advanced technology, they can reliably block limited strikes and are vulnerable only to large-scale salvos which are much easier to be stopped pre-emptively. However, manoeuvring missiles flying at hypersonic speed, or more, are impossible to intercept as of now. While there are prospective systems that could be getting such capability, like the S-500, as well as the existing 53T6 “Gazelle” ABM, the probability of intercept is likely to be exceptionally low. Furthermore, the cost of those interceptors is astonishing with Russia holding only 68 of 53T6 missiles in silos for antiballistic defence of Moscow.

As of now, there are 3 ways to make such manoeuvring hypersonic weapons. First type of such weapon is a hypersonic glide vehicle. Here, rocket (like a ballistic missile) boosts the glide body to high hypersonic speed. After hat, the glider skips atop the highest levels of atmosphere, manoeuvring during its path until ultimately hitting the target. Weapons of this kind are the fastest as of now (although by gliding they slowly lose their speed of the course of the flight), but they require larger ballistic missiles to power them. Russian Avangard system is the silo based strategic system of this kind, currently mounted upon a UR-100N ICBM. Chinese DF-17 mounted upon MRBM is a road mobile glider meant to be used within a theatre. American AGM-183 ARRW is a prospective glider meant to be used within a theatre via strategic bombers as launch platform. Second type of hypersonic weapon is a cruise hypersonic missile. Like regular cruise missiles, these are utilizing a cutting-edge jet propulsion system known as scramjet to sustain their speed for longer duration than the rocket motor while cruising in the atmosphere. It should be noted that these missiles will have to fly fat higher than, for example, Tomahawk, since atmospheric drag at greater heights is far lesser. The only tested weapon of this type is ship and submarine-based Zircon anti-ship missile which will enter service with the Russian Armed Forces in 2022. BrahMos 2 is an Indo-Russian joint project of another hypersonic anti-ship missile. American experimental weapon of this type is HAWC. Third type of hypersonic weapon is a quasi-ballistic missile. Like regular ballistic missiles, they fly up and fall down at great speeds. However, unlike ballistic missiles their trajectories are far flatter remaining in the atmosphere. They are also able to manoeuvre during different stages of the flight. Kh-47M2 is a Russian ALBM which falls under this category and it is using MIG-31 K as the launch platform. Another missile of this kind is Indian Shaurya missile, which is using submarine as a launch platform.

There are several kinds of these weapons coming and they will affect international security in the coming decades. Further articles will explore how these weapons will affect theatres of conflict and nuclear strategic balance, as well as how effects of these weapons could be managed by international actors.

[1] SR-71 is no longer in service, and MIG-25 is rarely used nowadays due to poor performance in several aspects.