The USA could have a counter hypersonic weapon developed by the mid-2020s.

However, creating a workable defense against hypersonic vehicles and missiles would require developing longer range radars and new space-based sensors to track and target an adversary’s weapons soon after they are launched, said Michael Griffin, undersecretary of defense for research and engineering, at a National Defense Industrial Association event on 13 December, according to a transcript and press release from the Pentagon.

The Department of Defense believes that the stage to knock out hypersonic weapons is during their relatively long cruise phase, in which they don’t change course abruptly. Hypersonic missiles during that stage are not particularly hard to intercept, but it would require an advanced warning, says Griffin.

Unfortunately, current US radars can’t see far enough.

“They need to see thousands of kilometers out, not hundreds,” he says.

The problem is compounded by the vastness of the Western Pacific Ocean and the lack of islands suitable to host radar installations.

“It’s not littered with a lot of places to park radars, says Griffin. “And, if you found some, they’d likely become targets.”

What’s more, hypersonic weapons are difficult to track via existing space-based sensors, he adds. Hypersonic weapons targets are 10 to 20 times dimmer than what the USA normally tracks by satellites in geostationary orbit, he says. And so, the USA would likely need to combine radar with a network of space-based sensors to effectively track and target an adversary’s hypersonic weapons.

“We can’t separate hypersonics defense from the space layer,” says Griffin.

The urgency in developing a defensive shield is driven by the fact that China is outpacing the USA in development of offensive hypersonic weapons. In August, the country reportedly conducted the maiden flight of a new hypersonic test vehicle, named Starry Sky 2, which boosts its speed by wave riding on its shockwaves. The vehicle reached Mach 5.5 for more than six minutes, and a topped out at M6, according to reports.

“In the last year, China has tested more hypersonics weapons than we have in a decade,” says Griffin. “We’ve got to fix that.”

If Russia – which is also developing hypersonic weapons – were to invade Estonia, or China were to attack Taiwan, it would be difficult to defend against their strike assets, he noted.