The Pentagon's hypersonic weapon programmes suffered a setback on Thursday when a booster rocket carrying a hypersonic weapon failed, people briefed on the test result said.
The test was intended to validate aspects of one of the Pentagon's hypersonic glide vehicles in development, two of the people said.
Hypersonic glide vehicles are launched from a rocket in the upper atmosphere before gliding to a target at speeds of more than five times the speed of sound, or about 6,200 kilometres per hour.
In a separate series of tests conducted on Wednesday, the US Navy and Army tested hypersonic weapon component prototypes. That test successfully "demonstrated advanced hypersonic technologies, capabilities, and prototype systems in a realistic operating environment," the Pentagon said in a statement.
The United States and its global rivals have quickened their pace to build hypersonic weapons - the next generation of arms that rob adversaries of reaction time and traditional defeat mechanisms.
US President Joe Biden expressed concern on Wednesday about Chinese hypersonic missiles, days after a media report that Beijing had tested a nuclear-capable hypersonic glide weapon.
Glide bodies are different from their air-breathing hypersonic weapon cousins which use scramjet engine technology and the vehicle's high speed to forcibly compress incoming air before combustion to enable sustained flight at hypersonic speeds. An air-breathing hypersonic weapon was successfully tested in September.
Companies such as Lockheed Martin and Raytheon Technologies are working to develop the hypersonic weapon capability for the United States.
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ