Dr. Eggman writes "In an interview with the Star-Telegram, the Air Force's chief scientist, Mark Lewis, talks about the USAF's latest research direction. The service is working on hypersonic missile and bombers for the purposes of reconnaissance and attack. In response to Chinese and Russian anti-satellite developments, the Air Force plans to develop weapons capable of sustained travel at Mach 6 to allow them to deploy against and take out anti-satellite launch sites before the enemy can fire their missiles. Furthermore, should the US spy satellite network be brought down, the Mach 6 recon flight systems would be capable of filling in. Air Force officials hope to deploy a new interim bomber by 2018, followed by a more advanced, and possibly unmanned, bomber in 2035."
We've discussed on a number of occasions the scramjet technology
that would power such vehicles.