continental US and the US has over 6,000 warheads which could destroy China several times over.  China moves away from "no first use" and that justifies the US for pre-emptive strike. You are clueless how ingenious China's "no first use" policy is for a weaker nuclear state like China and it prevents [force] China to reach nuclear weapon parity to survive if hostilities break out.

The moment China drops "no first use", it better prepares to how the world it has enough nukes to destroy any opponent several times over.

You should seriously study the concept of MAD and why China adopted "no first use".