China has confirmed it flight-tested a hypersonic missile delivery vehicle designed to carry nuclear war-heads.
On Wednesday, the Defence Ministry said the testing was for scientific purposes and not targeted at any country.
"Our planned scientific research tests conducted in our territory are normal," the Beijing Defence Ministry told Reuters. "These tests are not targeted at any country and at any specific goals."
The statement confirmed a report by the online Washington Free Beacon newspaper that the hypersonic glide vehicle (HGV) was detected flying at 10 times the speed of sound over China on 9 January.
A spokesman for the Pentagon said it was aware of the test.
Lieutenant Colonel Jeffrey Pool, a Pentagon spokesman said: "We routinely monitor foreign defence activities and we are aware of this test.
"However, we don't comment on our intelligence or assessments of foreign weapon systems. We encourage greater (Chinese) transparency regarding their defence investments and objectives to avoid miscalculation," he said.
The state-owned China News accused American media of using the test to "hype the 'China threat' theory".
Professor Wang Yuhui , a researcher on hypersonic flight control at Nanjing University of Aeronautics and Astronautics told the South China Morning Post China was technologically ready for such a test. Describing the carrier, Wang said: "With a speed of Mach 10 or higher, it cannot be caught or tracked because defence systems don't have enough time to respond".
Additional reporting by Reuters