US doesn't have FOBS capability, so they can't avoid China's launch on warning defenses. Furthermore, US doesn't have HGV so the missile response time for China will be in the range of hours to a dozen hours, instead of less than an hour.
Honestly if there is a nuclear ww3, I think the way it would start is China hitting first with airburst nukes from FOBS. It wouldn't necessarily be thousands of nukes, maybe just a dozen in order to EMP the whole continental US.
The nukes could come from anywhere (not only China has access to low orbit), so NK, Pakistan, terrorists whatever would be blamed in the immediate aftermath. There also wouldn't be too many deaths, but within days, society will collapse due to all electronic networks being knocked out.
Nevertheless, no matter how good China's counterforce attack is, they won't be able to stop US sea based nukes from launching, so mutual annihilation or massive losses for China too is still likely.
China says it will not use nukes first under any circumstance, but when it really came down to it, would the survivors sue Beijing for lying? All warfare is based on deception.
The new nukes for China are designed to have the lowest detection and reaction time of any in the world. That is not the characteristics of a revenge weapon.
