EXPLAINER-Why is North Korea testing hypersonic missiles and how do they work?

North Korea has tested a new solid-fuel hypersonic missile with intermediate range, it said on Wednesday, in an intensifying race for the next generation of long-range rockets hard to track and intercept. The United States, China, Russia and other countries have also been developing hypersonic weapons in recent years. Despite their name, analysts say the main feature of hypersonic weapons is not speed – which can sometimes be matched or exceeded by traditional ballistic missile warheads – but manoeuvrability.