Submission + - The Ultimate Tech the US, Russia, China and India All Want: Hypersonic Weapons (nationalinterest.org)
Hypersonic weapons--or ballistic weapons that can hit a target flying many times faster than the speed of sound have been hyped since the 1970s. Currently almost all of the major powers are trying to build them. The US and China seem to be the furthest along and are working on various types of systems. China hopes such weapons could be a game changer and deter any US actions in Asia.
There is however one big problem (besides the insane amount of technology to make them work considering their speed): a possible arms race and the threat they could lead to a nuclear war:
"According to some analysts, the development of hypersonic weapons creates the conditions for a new arms race, and could risk nuclear escalation. Given that the course of hypersonic research has acknowledged both of these concerns, why have several countries started testing the weapons?"