The Cold War arms race had an interesting side effect - both the US and Russia have thousands of warheads and thousands of delivery systems. Uniquely among nuclear powers, USA and Russia have the capability to deliver what is essentially a nation-scale Exterminatus strike on any other nation on this planet in a matter of about an hour. And because of the decades spent where both sides were expecting a total launch from the other, both the US and Russia have missile defenses capable of partially mitigating such an attack.
Each other nuclear power on Earth, China included, has a few hundred warheads available at most and not nearly enough delivery systems to get them all on target at once. If China were to launch everything they've got, simultaneously, against US missile defenses designed for defending against a full strike of several thousand incoming ICBM/SLBMs from the USSR, would any of them get through? Unlikely.
ETA: Editing here because it had slipped my mind just how enormous the gap in nuclear capability actually is. The US has in total produced approximately 70,000 warheads, and our current arsenal sits at around 6,100 weapons. The USSR produced in total around 55,000 warheads and Russia's current arsenal is estimated at around 6,800 weapons. For comparison, the best estimates of China's nuclear arsenal based on known sources of fissile materials available to them would put the maximum number of warheads available at somewhere around 600.
I agree that they are not on par with our arsenal or defense system but I think you are overestimating the capability of our nuclear defense. The iron dome (provided by us) is widely regarded as one of the best if not THE best missile defense system. According to analysts it has around a 90% success rate in missile interception. Extrapolating that rate to a full Chinese assault means that around 540 (90%) of nukes would be stopped and approximately 60 (10%) nukes would hit. This would be a devastating attack and while all of china would probably turned into dust finer than the surface of the moon, It wouldn't be a ideal result for us.
This. One nuclear power is not equal to another.
The Cold War arms race had an interesting side effect - both the US and Russia have thousands of warheads and thousands of delivery systems. Uniquely among nuclear powers, USA and Russia have the capability to deliver what is essentially a nation-scale Exterminatus strike on any other nation on this planet in a matter of about an hour. And because of the decades spent where both sides were expecting a total launch from the other, both the US and Russia have missile defenses capable of partially mitigating such an attack.
Each other nuclear power on Earth, China included, has a few hundred warheads available at most and not nearly enough delivery systems to get them all on target at once. If China were to launch everything they've got, simultaneously, against US missile defenses designed for defending against a full strike of several thousand incoming ICBM/SLBMs from the USSR, would any of them get through? Unlikely.
ETA: Editing here because it had slipped my mind just how enormous the gap in nuclear capability actually is. The US has in total produced approximately 70,000 warheads, and our current arsenal sits at around 6,100 weapons. The USSR produced in total around 55,000 warheads and Russia's current arsenal is estimated at around 6,800 weapons. For comparison, the best estimates of China's nuclear arsenal based on known sources of fissile materials available to them would put the maximum number of warheads available at somewhere around 600.
I agree that they are not on par with our arsenal or defense system but I think you are overestimating the capability of our nuclear defense. The iron dome (provided by us) is widely regarded as one of the best if not THE best missile defense system. According to analysts it has around a 90% success rate in missile interception. Extrapolating that rate to a full Chinese assault means that around 540 (90%) of nukes would be stopped and approximately 60 (10%) nukes would hit. This would be a devastating attack and while all of china would probably turned into dust finer than the surface of the moon, It wouldn't be a ideal result for us.