There are videos of hypersonic missiles in the Ukraine. The hot plasma glows in front of the missile and a ground-to-air missile sent to catch the thing is slow like an airsnail in comparison.
I've read about the Chinese shockwave wind tunnels 20 years ago. They do a lot of basic research instead of relying on computer simulations like the West does. The Russians have the materials that can withstand the heat of the plasma caused by the compressed air. I'm sure that there was some technology transfer because for hypersonic missiles you need both the fluid dynamics and the material.
We've had the tech and materials to resist plasma at 17,500 mph as the space shuttle reenters the atmosphere in the 1970s. That's roughly 20x the speed of a hypersonic missile.
I'm not in the defense industry so I don't know exactly what level of real world testing takes place anymore. In years past, we did every real world evaluation possible. I did work for Mil/Aero in the semiconductor biz in the 1980s and we performed every real world test possible on the devices destined for space and military applications. That's why a simple 14, 16, 20 pin dip, flatpak packaged device was priced around $1 for the commercial pdip device, ceramic packaged same die for Mil was priced over $300 each (at that time, +/-40 years ago). There was centrifuge, gross and fine leak, temperature extremes, RADHARD, and a multitude of other tests and inspections performed over and above what the commercial grade parts received.
Sounds like a lost art to me. The main purpose of the defense industry of today is to create kickbacks for congress, they'll cut all corners possible.
Hypersonic speed is easy in the upper atmosphere, but doing it at sea level is a different beast. Ballistic missiles can withstand the heat until impact, but to be called a hypersonic missile, the machine must be able to change course under these conditions without burning its fins.
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