[greedo]

You know this? You have intel (that's probably classified NOFORN) or you've just read about Zircon? The Russians can hype their wunderwaffen til the cows come home, but they haven't demonstrated reliable, deployable systems.

If you think hypersonic weapons are any deterrent to the US involvement in Ukraine, you're just being silly. The Russians don't even have enough Kalibr cruise missiles to take out a 3rd rate military. They don't have enough money (or perhaps just too much corruption) to install active defenses for their MBTs (no Arena/Trophy).

The only reason we don't have US troops in Ukraine is because of the SS-18 Satan and Bulava SLBM.

And no one has an effective defense against the number of ICBMs/SLBMs on each side. The ABM systems around Moscow are too few to counter the number of warheads assigned, and the US missile defense is too raw (and also out of position) to defend against Russian missiles.