> There's a reason all modern silo based (and submarine) ICBMs are solids.

Believe it or not, here in 2026, this is incorrect!

Those crazy Russians:

https://en.wikipedia.org/wiki/R-29RMU_Sineva

https://en.wikipedia.org/wiki/R-29RMU2_Lajner

UDMH + nitrogen tetroxide.

I would not want to be a Russian submariner. For all sorts of reasons.