Stratolaunch completed two flights of its autonomous Talon-A2 rocket plane earlier this year, as the US aims to gain ground in its race for hypersonic supremacy with China.

The U.S. set records in the 1960s with the rocket-powered North American X-15 aircraft. ... California, has built the first hypersonic aircraft to land since the X-15 was shuttered in 1968.

NASA’s X-43A was a small, unmanned experimental aircraft that, in 2004, shattered world records by flying at nearly Mach 10 (almost 7,000 mph), becoming the fastest air-breathing vehicle in history.