China and Russia are the two countries which have successfully tested hypersonic missiles. Hypersonic missiles are the missiles which are flying below 90 km in the atmosphere at a speed of Mach number 5 and above. Mach number means the speed of an object with respect to the speed of sound. A Mach 5 missile will be flying at a speed of 5 times the speed of sound. 

Hypersonic missile "concept"

At a high speed there is a large generation of heat on the surface of the missile which leads to a very high heat load. Air which consists of molecules begin to dissociate at this very high speed. Speed above Mach 25 has been achieved in the atmosphere. This speed is of the space shuttle and spacecraft which return to earth after completing the orbit around it. 

Space Shuttle - Entry

Hypersonic cruise missile and hypersonic glide vehicles at present are the two technologies which can travel at hypersonic speed. Hypersonic cruise missiles are powered by Scramjet engines. Scramjet engines are air breathing engines which do not have any moving parts. It is an advanced version of Ramjet engine where the combustion is entirely supersonic, so is the name Supersonic Combustion Ramjet engine. 

France, India, Australia, Germany and Japan have hypersonic research programs.