This is getting very silly indeed. The AIM-9 long ago ceased to have any parts in common with the original. Now it’s not going to even look vaguely similar – yet it’ll be called not a new missile, or even a new mark of the old one, but a sub-variant of an existing mark. Doh! Is the US weapons designation system broken, or just lapsed into self-parody?

AIM-9X was bad enough, a mistake in the same category as calling the JSF F-35 (carry over the designation of a development item to a production weapon), but now to adopt it as the designation of any IR-guided US AAM is downright stupid. AIM-9X was originally a placeholder designation, deliberately chosen to be out of sequence & thus not confused with a real designation, & referred to all projects for a follow-on to the AIM-9 after AIM-132 was dropped by the USA.

IIRC AIM-9X should have been AIM-9T (next unallocated designation). ‘Block II’ should probably have been AIM-9U, & ‘Block III’ should definitely be a new missile, the next in the (AI)M- series – which was up to FGM-172 last I heard.