The Pentagon's top general Mark Milley stated on Wednesday that China's recent test of an earth-circling hypersonic missile was similar to the Soviet Union's launch of the world's first satellite, Sputnik, in 1957.

I am stunned and saddened that my Chinese counterparts did not call me first, as I have always done for them. https://t.co/e9V6kyf6mU

— General Milley (@GeneralMiIIey) October 27, 2021

"What we saw was a very significant event of a test of a hypersonic weapon system. And it is very concerning," Milley told Bloomberg TV.

"I don't know if it's quite a Sputnik moment, but I think it's very close to that," he added.

On its account, the US Department of Defense had previously declined to confirm the test, which was first reported on October 16 by the Financial Times.

According to the Financial Times, the missile circled the Earth at a low altitude, at a velocity of more than five times the speed of sound, but it missed its target by more than 30 kilometers (19 miles).

China denied the report, saying that it was merely a routine test of a reusable space vehicle.

In a White House briefing on Wednesday, White House Press Secretary Jen Psaki acknowledged Milley's remark, saying, "I believe he was expressing our collective concern about China's military modernization efforts. They continue to pursue capabilities that exacerbate regional tensions, and we remain concerned about this."

What do you need to know?

China conducted a test of a nuclear-capable hypersonic missile in August that circled the globe before rushing towards its target, revealing its sophisticated space capability that caught US intelligence off guard.

Five sources familiar with the test reported that the Chinese military fired a rocket carrying a hypersonic glide vehicle that traveled through low-orbit space before descending to its target.

According to three informed persons, the missile missed its target by roughly two dozen miles. However, two experts claimed the test demonstrated that China had made incredible progress on hypersonic weapons and was far ahead of US officials.

The test has raised new questions about why the US has consistently miscalculated China's military development efforts, “We have no idea how they did this", said the fourth person. 

The US, Russia, and China are all working on hypersonic weapons, such as glide vehicles that are sent into space on a rocket but orbit the globe on their momentum. They travel at five times the speed of sound, a fraction of the speed of a ballistic missile.

They are, however, agile and do not follow the fixed parabolic trajectory of a ballistic missile, making them more difficult to track.

What Are Hypersonic Missiles?