North Korea last month fired a ballistic missile capable of hitting the US territory of Guam, the latest in a record flurry of tests that demonstrated the unrelenting progress of the country's illicit nuclear weapons programme.
But of all the missile systems tested in recent weeks, it is the development of a new generation of manoeuvrable weapons designed to evade missile defence systems that has most intrigued defence experts.
“Kim Jong-un [the North Korean leader] doesn’t just want more missiles, he wants better missiles,” said Ankit Panda, a nuclear weapons expert at the Carnegie Endowment for International Peace.
“The qualitative arms race has kicked off in a very big way.”
Unlike a ballistic missile, which follows a predictable parabolic trajectory affected only by gravity and atmospheric drag, a manoeuvrable missile’s path can be changed mid-flight through the manipulation of fins or winglets and, in some cases, propulsion systems such as air-breathing engines.
On January 5th, North Korea’s Academy of National Defence Science oversaw the launch of a rocket fitted with a conical “manoeuvring re-entry vehicle” (MaRV).
According to North Korean state media, the vehicle made a “120km lateral movement in the flight path” before hitting its target in waters 700km from the launch site in the northern Chagang province.
Six days later, a leather-clad Kim attended the test of a rocket fitted with a “hypersonic gliding warhead” that made a “gliding re-leap” and 240km lateral manoeuvre before hitting its target.
Such weapons are often described as “hypersonic”, a term used to describe any projectile that travels at five times the speed of sound or faster. But experts stressed that it was the weapons’ manoeuvrability, not their speed, that distinguished them from other types of missiles.
"There are really three motivations for developing manoeuvrable missiles," said Steven Dunham, a launch systems analyst at The Aerospace Corporation, a US federally funded research and development centre in Los Angeles.
“First, you’ve got to hit the target you want to destroy with the accuracy that’s required. Second, in order to do that, you need to be able to evade or avoid the missile defences that surround the target. And third, you need to have the range in order to be able to reach that target,” he said.
Missiles able to change their trajectory can be both more precise and much harder to intercept and destroy.
Delivery vehicles that glide at low altitudes are also more likely to evade the attention of radar systems – such as South Korea’s Terminal High Altitude Area Defence system – that are designed to detect ballistic missiles travelling at much higher altitudes.
The US, China, Russia, Iran and South Korea, among others, have been developing manoeuvrable missiles, in some cases for decades. Last year, the Financial Times revealed that China had tested a hypersonic glide vehicle capable of orbiting the globe before re-entering the earth’s atmosphere.
"There is a misapprehension that manoeuvrable weapons are some kind of new, niche threat," said Sam Wilson, senior policy analyst at The Aerospace Corporation. "In fact, most missiles being developed around the world are manoeuvrable to some degree."
Risk of miscalculation
But analysts worry that North Korea’s manoeuvrable weapons, in addition to the progress it has made developing “solid-fuel” missiles that can be deployed with less warning, raise the risk of a disastrous miscalculation on the Korean peninsula.
South Korea’s defence strategy envisages “kill chain” pre-emptive strikes against North Korean missile systems in the face of an imminent attack.
Last month, Yoon Seok-youl, the conservative candidate in March’s South Korean presidential election, said a pre-emptive strike was the “only method” of preventing an attack from a nuclear missile capable of travelling at hypersonic speeds.
“What’s concerning is that if you look at North Korea’s plans to shoot first, and you look at how South Korea plans to react to North Korea’s plan to shoot first, you realise that both their policies are to shoot first,” said Carnegie Endowment’s Panda. “It’s the classic reciprocal fear of surprise attack scenario.”
Observers said Pyongyang would continue to exploit a divided and distracted international community as it checks off items on a weapons wish list announced by Kim last year.
“For the US to break the impasse, it has to give the North Koreans something ‘big’, and that would require giving sanctions relief of some kind,” said Sue Mi Terry, a former CIA analyst based at the Wilson Center think tank in Washington. “But how can the Biden administration realistically do so when the North tested seven missiles in 25 days?”
In the meantime, said Aerospace Corporation’s Dunham, it was imperative that defence planners started to put manoeuvrable weapons at the heart of their thinking.
“This evolution towards manoeuvrability really threatens the foundation of our historical approaches to both missile defence and missile warning systems,” said Dunham. “The threat has outgrown the language we have available to discuss and define the problems that we need to solve.”
What are manoeuvrable missiles?
A missile system consists of a rocket – or booster – and a weaponised payload that delivers a warhead to its target. Some are non-separating or “unitary” missiles, while others have detachable payloads.
Ballistic warheads follow a predictable parabolic trajectory – akin to a cannonball – affected only by gravity and atmospheric drag.
Typically fitted to ballistic missile boosters, aerodynamic vehicles are weaponised payloads that can be manoeuvred through the use of aerodynamic control surfaces such as fins and winglets.
There are several types of aerodynamic vehicles, including manoeuvring re-entry vehicles and hypersonic glide vehicles. While the term “hypersonic missile” is often used as shorthand for these manoeuvrable weapons, experts said this was misleading: almost all missiles that travel several hundred kilometres or more reach hypersonic speeds.
A fractional orbital bombardment system is a delivery system that sends a weaponised payload into orbit, where it circles the earth until a rocket attached to the warhead slows it down and allows it to re-enter the earth’s atmosphere and speed towards its target. – Copyright The Financial Times Limited 2022