IT’s another example of the game of military leapfrog played ever since the first caveman hefted a rock.

Others immediately start looking for a better weapon.

It’s happening again.

The United States is concerned it has lost the technological edge when it comes to a new arena of warfare: hypervelocity missiles.

These are themselves a response to the increased capability of modern defensive systems.

Cruise and ballistic missiles can now be targeted. Ship, ground and air launched interceptors can destroy them before they reach their target. And even if they get close, radar-guided robotic gattling guns have a last-ditch chance of knocking them from the sky.

What makes a hypervelocity missiles so potent is they are fast.

Very fast.

So fast neither interceptor missile or bullet has enough time to act.

Late last year China declared it was on the brink of putting operational examples of this new weapon system into service.

The United States isn’t.

And that has The Pentagon worried.

”China’s hypersonic weapons development outpaces ours ... we’re falling behind,” Admiral Harry Harris — soon to be the next US ambassador to Australia — said late last week.

“We need to continue to pursue that and in a most aggressive way in order to ensure that we have the capabilities to both defend against China’s hypersonic weapons and to develop our own offensive hypersonic weapons.”

A CALL TO ARMS

A US Missile Defence Agency report reveals it has placed an urgent call to its suppliers for improved sensors capable of detecting — and tracking — hypervelocity missiles in flight.

It’s called for a new $9.9 billion budget for 2019.

It recognises the urgent need to improve its defences against this emerging threat.

Enormous nuclear-powered aircraft carriers suddenly seem vulnerable.

Large but static strategic bases — such as Guam in the middle of the Pacific Ocean — have little chance of countering such an attack.

Which is why Missile Defense Agency Director of Operations Gary Pennett told reporters during a recent budget briefing that it has identified “sensor and interceptor capability gaps”.

“The key challenge to US national security and the security of US friends and allies is the emergence of new threats designed to defeat the existing ballistic missile defence system,” he said.

In particular, he was worried about the speed of command and control networks needed to isolate the threat, and to inform units capable of doing something about it.

Where once they had minutes, they now have just seconds.

“Any software associated with any of those systems might have some capability to track hypersonic systems. This evolving threat demands a globally present and persistent space sensor network to track it from birth to death,” Pennett said.

The budget appeal comes just months after Chinese state media reports it had successfully tested hypersonic warheads and was now moving on to full-scale production.

This may have a lot to do with the US Missile Defence Agency’s new plans to install 64 Ground Based Interceptor facilities around the United States before 2023.

But North Korea is also another motivator.

ACHILLES HEEL

Chinese state media has boasted of the success of its new type of hypersonic missile, designated the DF-17. The US Director of National Intelligence has confirmed these tests actually happened.

Beijing may have achieved this lead as it is not subject to the same international arms control treaties as Russia and the United States.

But Russian state media has been making similar claims. It says its first example of the new technology will enter production later this year.

This looming new threat may explain the a US emphasis on improved detection and response systems: these target the one weak point hypervelocity missiles retain.

They need to be boosted into space.

Like intercontinental ballistic missiles, a large rocket must lift the warhead off the ground and propel it high into orbit. The higher and faster it is going when it reaches the top of its parabolic arc, the faster it can dive back into the atmosphere below.

From that point, things get difficult.

The smaller warhead glides at more than 6000km/h. But it can also twist and turn to avoid detection and incoming fire.

So, like ICBMs, shooting it down during its heavy-and-slow launch phase is the easiest option.

And for its deadly fast glide phase, the earlier it is detected — the greater the chance of calculating a shoot-down solution.

Both need reliable information, fast.

Thus the emphasis on researching new long range / high accuracy sensors and command-and-control processes.

But also in the works is a redesigned ‘kill vehicle’ interceptor warhead, improving the chances of taking down a high-energy opponent.