Explained: Hypersonic Glide Vehicle, The New Focus Of Global Arms Race

On the new year’s eve last year, Russia announced that its new hypersonic glide vehicle (HGV), Avangard, launched atop an intercontinental ballistic missile, had been made operational.

While Russia has beaten its rivals United States (US) and China in the launch of HGV, they are also close on the heels.

While the US has moved from the research to the development stage of HGV, China has demonstrated the DF-17, a medium-range missile with the HGV, at a recent military parade.

What HGV?

A HGV is the only operational military application of the concept of boost-glide. Boost-glide extends the range of ballistic missiles, roughly double that of the purely ballistic trajectory.

It combines the speed of intercontinental ballistic missiles with the accuracy of cruise missiles.

A hypersonic delivery system can fly at speeds higher than 5 Mach (five times the speed of sound) at lower altitudes. It can execute a high degree of manoeuvres.

In comparison, a ballistic missile is not necessarily slower, and many times even faster than a HGV. However, a ballistic missile has predictable signatures and flight trajectory of a ballistic arc - going high up, and then back down on the target.

This kind of predictability means that the adversary can know about the launch via satellites tracking the tell-tale signs of one of these rockets blasting off from a launch pad.

Additionally, the relatively uniform flight trajectory means that the air defence systems, at least in theory, can intercept these.

On the other hand, in HGVs like Avangard use air-breathing engines that generate a very different signature from a rocket motor, making detection of launch and tracking the device difficult.

On top of that, the low flying HGVs are capable of fling in more erratic ways well within the atmosphere. It may change course mid-flight rather rapidly. This enables it not only be more accurate, but also possibly evade the most fast-scanning surface- and airborne radars that exist at present.

Also, with such an immense speed and erratic trajectory, it would be hard to intercept.

While the fundamental technology behind HGVs is decades old, but the latest developments in materials science, weapon systems, and growing concerns about missile defence systems has led to a recent push for deployable HGV payloads.

Avangard and further developments

The Avangard can have either, conventional or nuclear warheads. Russia claims that this nuclear-armed HGV can fly at over 20 times the speed of sound.

Due to its manoeuvring, it becomes “invulnerable to interception by any existing and prospective missile defence means of the potential adversary”, Russia says.

After US walked out of the anti-ballistic missile treaty in 2002, both China and Russia became cautious of latter’s ballistic missile defence (BMD) system.

Russia and China explain away developing HGV as regaining lost strategic stability - as they feel that the US BMD has eroded their nuclear deterrence.

On the other hand, US says that the development of HGV is in pursuit of prompt global strike strategy, mainly for attacking time-sensitive targets any where on the planet.

Therefore, reportedly, Russia has declared HGV as nuclear capable, China as dual-use capable, and US as conventional.

The HGVs increase the risk of misperception, as an incoming HGV can bring in both nuclear and conventional warheads. Over this, is the destination ambiguity - where the missile is headed - whether is it targeting the nuclear arsenal to reduce the capability of retaliation.

These ambiguities may force the nations to assume the worst, and take more forward postures to increase deterrence like launch on warning or launch under attack.

A counter-race will also start for developing more effective missile defence systems and new technology to defeat hypersonics, along with the HGVs themselves.