Status-6 Oceanic Multipurpose System (Poseidon)
en.wikipedia.org
en.wikipedia.org
It seems like this allows more orgs within Russian military industrial complex to grab development money. It probably reduces their perceived need to pay for the manned submarine leg of the nuclear tripod in the upcoming decades.
Status-6 seems like a hedge against the possibility of those SLBMs being rendered obsolete by a theorized missile defense program like Brilliant Pebbles: https://en.wikipedia.org/wiki/Brilliant_Pebbles
Brilliant Pebbles called for thousands of satellites in LEO, which was impractical when it was originally proposed. But SpaceX has since demonstrated their ability to launch constellations this large on a relatively small budget.
[0] https://www.researchgate.net/figure/Radio-wave-attenuation-b...
I'm former Air Force, so that sort of comes with the territory. Sorry. :)
https://en.m.wikipedia.org/wiki/Submarine_navigation
It's not mentioned in the article, but I believe US subs also have a long-tether communications buoy that can float to the surface, but not expose itself vertically, to communicate with satellites. I would be surprised if it did not also have a GPS antenna.
Also, it's not about rationality at all, North Korea has so far behaved perfectly rationally.
Multiple contracts were awarded for space-based missile tracking system that were specifically meant to deal with HGVs, so yes, there is another missile defense in the pipeline, that Pompeo literally called "SDI II".
For the record, it's also not clear with Status-6 is operational, either. But the technology behind Status-6 is pretty much all stuff that we already know they have working, whereas HGVs maybe not so much.
US Generals have said quite plainly that Russia and China are simply ahead in hypersonics, and I'm sure if the demonstration of Avangard to the US was dodgy they'd be called out.