... here we see a Sprint anti-missile-missile [ABM] being loaded into a silo launcher for a test at White Sands, NM. Sprint was the third phase, low level, interceptor of the 'Safeguard' system. If incoming warheads made it past the other missiles designed for outer-space or high altitude interception, Sprint would go screaming out and zap them with an enhanced radiation small nuke at lower altitudes. How low? From around 20 miles down to the last mile. Wow- better make sure you've got your Ray-bans on!
This is truly an "Oh-shit!" defense system. This cocaine snorter went from a standing start to 7,600 mph in just 5 seconds! In this video you can clearly see the second stage as it becomes white hot from atmospheric friction.
... sort of like it won the race and is in the next county before your big brother's GTO has even moved off the starting line!