To me it looks like Russia is trying to test if their ICBMs will get through western air defense as they had troubles with their Kinzal/Iskander ballistic missiles being shot down in some scenarios. There were also purges on Russian side because of this - https://mil.in.ua/en/news/russia-imprisoned-12-scientists-in...

I think there is no utility of using ICBM for targeting anything using conventional warhead. CEP is 100m and more, it is just waste of military resources.

So my guess is a test / show of force / terror bombing. Probably all 3 at the same time.