His barometer for a nation's threat to America was a pointless theater exercise? (Because duck and cover would have done jack against an actual nuclear strike.)
Given the rest of his performative Twitter timeline, that's rather fitting.
Duck and cover is an absolute necessity in a nuclear strike, it will prevent countless injuries and deaths.
It was practical training when dads still were heads of households and many millions had learned what flying debris can do in WWII and Korea, and in Japan where protection from the flash and blindness also mattered.
We still do it for tornados and hurricanes but the left mocks it for explosions.