If Putin holds a sham referendum in the south and east of Ukraine, he may see part of Ukraine as Russian territory, and will have an excuse to launch tactical nukes to defend it.

It seems more a maneuver that lets him put conscripts on the ground there. Russia has a law against putting conscripts anywhere but on Russian territory. Not sure that matters, but for a country essentially run by gangsters, Russia is oddly legalistic (e.g. soldiers can break contracts, refuse to fight with no jail sentence because it's not a declared war).

Putin could very well just buy the expertise and technology he needs from China.

Trivia: Back in the 80s, I had a job offer from Raytheon to work on missile software as I was an 8086 assembly-level hotshot and their guidance systems used a ‘hardened’ version of an Intel chip with a similar instruction set — or so I was told at the interview. China seems to be able (just!) to produce chips with similar power — but probably not ‘hardened’ versions. China’s attempts to produce anything beyond low-capability chips haven’t turned out well. Also, I was a little boggled that Raytheon would use an 80x-anything. Might have had to do with what was produced in the US. I’d have picked a Z80.

Oh, and from what I understand about MIRVs, that’s an incredibly specialized technology. I worked with one of the guys who’d been on the Apollo computer team, ended up talking with some of his friends about MIRVs over beers one night.