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. 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 realised. The test has raised new questions about why the US often underestimated China's military modernisation. "We have no idea how they did this," said a fourth person. The US, Russia and China are all developing hypersonic weapons, including glide vehicles that are launched into space on a rocket but orbit the earth under their own momentum. They fly at five times the speed of sound, slower than a ballistic missile. But they do not follow the fixed parabolic trajectory of a ballistic missile and are manoeuvrable, making them harder to track. Taylor Fravel, an expert on Chinese nuclear weapons policy who was unaware of the test, said a hypersonic glide vehicle armed with a nuclear warhead could help China "negate" US missile defence systems which are designed to destroy incoming ballistic missiles.