Re: How fast is 'fast moving'
Actually, there is a target drone that's designed to simulate the likes of Sunburn and Brahmos
https://www.defenseindustrydaily.com/gqm163-ssst-a-tricky-coyote-to-match-wits-with-defenses-03155/
It's just rather expensive, so not used that often. We should also bear in mind that Sea Ceptor is derived from Asraam, which as an air to air missile is designed to intercept supersonic targets anyway...no comment on the difficulty of doing so a few metres above sea level!