I think that it's all about the US trying to con Russia into an arms race again. The US has the resources to win it while Russia gets hurt on the economy side.
Russia/Putin have claimed that Russia won't be drawn into an arms race again. Will they?
As you suggest, Russia has pursued a deterrent against US aggression with it's unstoppable hypersonic missiles. But all that is really important is that neither side is going to start a nuclear war. This fact prohibits a head to head conflict between the world powers and then limits US aggression to proxy wars.
Syria is done and Russia won. Iran is next but Russia seems to be saying that Iran isn't on the table. And European countries are not cooperating with US demands and plans for Iran.