Apparently the russians are working on Mach 3 and beyond nuclear powered cruise missile, a successor to Burevestnik.
Something that i wanted to say for a long time, and perhaps there might be a better topic for this discussion, but i think whatever the logic the russians followed when seeing the need for Burevestnik and Poseidon (basically making sure that they can ensure MAD even in the face of american ABM and other missile defences), it's even more imperative China develop their own equivalents, since it has a much smaller nuclear arsenal than US, hence more vulnerable to being degraded below necessary MAD levels by US ABM and other defences. Given the increasingly erratic and volatile western behaviour, it is not unlikely that decision making actors such as the orange potus and his cronies/handlers might think they can actually win a nuclear war against China because it has much fewer nukes and the US ABM will protect their mainland from most damage. It's an unnerving thought considering the unpredictable behaviour displayed in this last year by the US and western axis.
Hopefully China is already working on such weapons in the shadows.