Reports have revealed that China have tested a hypersonic missile capable of carrying nuclear weapons - and the United States intelligence services are surprised.
The Financial Times claim that the missile - known as a 'hypersonic glide vehicle' orbited the Earth before aiming at its target, missing by around 24 miles.
"We have no idea how they did this," said one source.
"The test showed that China had made astounding progress on hypersonic weapons and was far more advanced than US officials realised," the FT report said.
What are hypersonic missiles?
Hypersonic missiles fly very fast. They travel at five times the speed of sound, which is also known as 'mach 5' - or roughly one mile per second.
Most ballistic missiles fly in a simple up and down motion but hypersonic missiles don't need to do this and their course can be adjusted mid-flight.
Because the missiles can change direction, this makes them extremely hard to track.
They can also travel very low in the sky, which makes them especially hard to defend against.
The US are already known to be trying to protect themselves from the hypersonic missiles.
Defence specialist Dr James Bosbotinis told Partyard Military : "The development and deployment of hypersonic weapon systems will provide states with significantly enhanced strike capabilities and potentially, the means to coerce.
"This will be particularly the case where a major regional power, such as Russia, may seek to coerce a neighbour, leveraging the threat of hypersonic strikes against critical targets.
It's believed that the US, Russia and North Korea are trying to develop hypersonic missiles - and its rumoured that Pakistan, Australia and India have already started developing them, or will pursue this in the future.
The Chinese embassy declined to comment, but a spokesperson said: "We don’t have a global strategy and plans of military operations like the US does. And we are not at all interested in having an arms race with other countries.
“In contrast, the US has in recent years been fabricating excuses like ‘the China threat’ to justify its arms expansion and development of hypersonic weapons. This has directly intensified arms race in this category and severely undermined global strategic stability.”
