There’s a thing that has to be taken into account though, regarding the speed of these missiles; ballistic ones are faster, but reach Mach 20 and similar speeds outside of the atmosphere, while hypersonic missiles reach up to Mach 5 in the atmosphere.
Anyways, “hypersonic” would be a much better term to use for that technology than Trump’s “super duper missile”...
Exactly, ballistic missiles (or, at this point of the strike, their warheads) are slowed down when reentering the atmosphere—just like satellites and space capsules containing astro/cosmo/spationauts—at much slower speeds. The 2-digit Mach speeds are reached only outside of the atmosphere.