ABM systems.
This website is worth adding to your favorites. Loads of great information on the Sentinal/Safeguard ABM systems of the 1960s/70s.
"To say Sprint was a phenomenal missile, is putting it mildly. A cone shaped missile that accelerated at 100g, achieved a speed of Mach 10 in 5 seconds, had an ablative coating to dissipate the heat that was generated from the friction from the atmosphere and was so accurate that the radar had to be de-tuned during testing so that it would not hit incoming RVs. It was a phenomenal missile."
This was with 1950s/1960s technology. Makes me wonder how far advanced our ABM systems would be today had they not been killed by idiot politicians.