WNU editor: From CNBC ....
.... Hypersonic air travel is anything that travels at Mach 5, or five times the speed of sound. The U.S. was once a leader in developing supersonic and hypersonic technology, but has taken "our foot off the gas," according to Mark Lewis, executive director of the National Defense Industrial Association's Emerging Technologies Institute.
Watch the video to find out more about how the U.S. fell behind Russia, China and possibly North Korea, and how we're spending billions to catch up.