What are hypersonic weapons?

The term ‘hypersonic’ denotes speed that’s five times faster than sound. The speed of sound is around 760 miles per hour at sea level. This means, hypersonic weapons can travel at speeds of at least 3,800 miles per hour.

However, ballistic missiles also travel at hypersonic speeds, especially in the re-entry phase. So, what sets apart new-age hypersonic weapons from the missiles of the past?

According to US Congressional Research Service, hypersonic weapons don’t follow a predetermined, arched trajectory like ballistic missiles usually do. Furthermore, they can maneuver on the way to their target.  
In effect, you get a very fast, low-flying, and highly manoeuvrable missile that could prove to be too quick and agile for existing missile defence systems to react.

New-age hypersonic weapons fall in two broad categories. These are cruise missiles and glide vehicles.

Glide vehicles are launched from a ballistic missile. Once they reach the required distance and speed, they glide to their target at hypersonic speeds.
Hypersonic cruise missiles might employ scramjet engines that enable them to cruise at a steady altitude and with sustained speeds.

Now, let’s come to the missile that was recently used by Russia.   
According to US think-tank Centre for Strategic and International Studies, the Kinzhal is an air-launched ballistic missile. It is nuclear-capable. And, it travels at 10 times the speed of sound. It is understood to be capable of overcoming many existing air-defence systems. The missile has a range of approximately 1,500-2,000 kms.
 
Note that this weapon is neither a glide vehicle nor a cruise missile. Therefore, it might be somewhat misleading to put it in the same category as the new-age, advanced hypersonic weapons that are being developed by the major powers.

The US, China and Russia possess the most advanced hypersonic weapons programmes. However, Australia, India, Germany, France and Japan are also developing hypersonic weapons.
 
So, where does India stand?
India is close to fielding the BrahMos-II which is a hypersonic cruise missile under development in collaboration with Russia.
 
As a part of its Hypersonic Technology Demonstrator Vehicle programme, India is also developing an indigenous hypersonic cruise missile. In fact, India had successfully tested a Mach 6 scramjet in June 2019 and September 2020.