I was checking my data for a Book I am considering writing

[DrainBamage]

The most successful intercept program for USA has been SM-3/Aegis Ashore, which is hit-to-kill (not blast frag), however that is insanely expensive and has proven itself against IRBMs which while reaching extremely high speeds also follow a predictable ballistic trajectory that is much easier to detect and intercept than hypersonic missiles. Also SM-3 is designed to kill targets in upper atmosphere, which might apply to the boost phase of boost-glides (I have no idea) but would be useless against hypersonic cruise missiles. It's conceivable that THAAD or Patriot PAC-3 could be improved to engage hypersonics, assuming sufficient detection was possible.