China tested a nuclear-capable hypersonic missile in August that circled the globe before speeding towards its target, demonstrating an advanced space capability that caught US intelligence by surprise, Financial Times reported.

Five people familiar with the test said the Chinese military launched a rocket that carried a hypersonic glide vehicle which flew through low-orbit space before cruising down towards its target.

The missile missed its target by about two-dozen miles, according to three people briefed on the intelligence. But two said the test showed that China had made astounding progress on hypersonic weapons and was far more advanced than US officials realized.

“We have no idea how they did this,” said a fourth person.

Two of the people familiar with the Chinese test said the weapon could, in theory, fly over the South Pole. That would pose a big challenge for the US military because its missiles defense systems are focused on the northern polar route.

The Pentagon did not comment on the report but expressed concern about China. “We have made clear our concerns about the military capabilities China continues to pursue, capabilities that only increase tensions in the region and beyond,” said John Kirby, spokesperson.

The Chinese embassy in the US declined to comment on the test, but Liu Pengyu, spokesperson, said China always pursued a military policy that was “defensive in nature” and its military development did not target any country.