My personal guess is the following.
Since the 1980s and 1990s of intense Soviet and American BMD competition and nuclear treaties and BMD treaties, China was watching closely. All three of these players have been developing and firing BMD missiles since the 1970s at least for China, with the other two, possibly earlier. Chinese BMD and early warning programs go FAR back.
Since the 1980s they realised BMD is the real playing field and the two Cold War adversaries countered each other with placating treaties and formalities while rushing BMD development and manufacturing. They also both insisted on more warheads that can cover the planet's entire habitable areas. Why? It's not only due to foolishness and ego but there truly was a need in the era of very capable BMD. This has been the case since the 1980s and the Chinese have been watching very closely the Cold War dynamics and moves.
Since the 2000s where GBI and THAAD, SM-3 and PAC-3 and so on were proliferating and assumed as highly capable and accurate, China's own latest BMD programs were coming to service. Its first kinetic kill ASAT weapon was used more than a decade ago now. China has been practicing its latest BMD systems on hypersonic maneuverable vehicles. We're in a new era.
But BMD developments made the PLA aware of the need for increased ICBMs and warheads if we average each ICBM as carrying let's say 3 active warheads, PLA has known for over 40 years that the only sure way of countering proliferating and capable US BMD is by saturation and improved missiles. First part they need to build up more missiles to counter boost (if any) and mid course interceptors. So if the US have roughly 1000 interceptors positioned right around China's northern to southern directions, then China needs around 1000 ICBM ranged missiles as a minimum. That's 3x the no. of warheads so roughly 3000 warheads just for this task. The second part is developing much more advanced missiles and warheads and these eventually were revealed to be hypersonic vehicles using the Qian Xuesen type trajectories possibly with more complex flight patterns and shockwave riding air breathing or not. This is still a bare minimum to counter known minimum numbers of US interceptors.
Concurrent to this is a new and vast network of land, sea, and space based early warning with plenty of redundancy and of course various types of fire on command etc organisational and communication developments and how they are administered. The Chinese BMD is also up and running from the seldom talked about HQ and SC series we've only had hints of and tests of.
TLDR:
During the period between the 1980s and now, China knew it absolutely had to build up stockpile to the minimum 1000 warheads. Honestly the minimum is more like 1000 ICBMs and SLBMs but it's unknown if the CCP went to that secure an extent. They definitely have the desire now and doing it if it hasn't already been done. It also knew it had to field a considerable quantity of BMD interceptors which at the high end of threat can buy it time for retaliation strike or at the low end, neutralise North Korean or Indian missiles convincingly as a secondary function with the primary one being buying time to launch retaliation strikes where most of their arsenal could be protected for long enough to launch.
It did all this long ago while placating the US with "I only maintain about France and UK's stockpile numbers and have absolutely a no first use, minimum deterrence nuclear posture".
There is no way an equally big and much more promising and high potential economy with four times more people to defend and retaliate for in case, would ever allow their main adversary to be able to intercept their entire nuclear arsenal with just BMD on a single warship. This is impossible. It is also a cheap and easy matter, costing China less than 1% of GDP for every year for maybe just 10 years to build up to US levels. It's so bloody obvious it's a no brainer but liberal arts intellectual masturbators prefer complicating simple things with their desire for intellectual masturbation. The reality is so obvious, you can use logic only to determine China's true nuclear size to a decently accurate degree. This puts China's prior to more recent build up to around 1000 warheads with /3 no. of >DF-31A ranged missiles.
China's military strategy has always been deterrence first and then conventional build up. China has been building warships and aircraft at a rate that suggests all this extra conventional build up is left over from first meeting and exceeding "minimum nuclear deterrence". By logic we can and have ascertained to a decent accuracy that "minimum nuclear deterrence" for China since at least 2000s means able to deliver unacceptable levels of destruction on the US in case the US conducts a first strike which would disable a sizeable number of Chinese nuclear arsenal and then put roughly 1000 interceptors into the air in the Pacific for Canada/Arctic, and another 1000 at least around the continental USA then another 1000 at least of terminal phase interceptors.
Since the 1980s and 1990s of intense Soviet and American BMD competition and nuclear treaties and BMD treaties, China was watching closely. All three of these players have been developing and firing BMD missiles since the 1970s at least for China, with the other two, possibly earlier. Chinese BMD and early warning programs go FAR back.
Since the 1980s they realised BMD is the real playing field and the two Cold War adversaries countered each other with placating treaties and formalities while rushing BMD development and manufacturing. They also both insisted on more warheads that can cover the planet's entire habitable areas. Why? It's not only due to foolishness and ego but there truly was a need in the era of very capable BMD. This has been the case since the 1980s and the Chinese have been watching very closely the Cold War dynamics and moves.
Since the 2000s where GBI and THAAD, SM-3 and PAC-3 and so on were proliferating and assumed as highly capable and accurate, China's own latest BMD programs were coming to service. Its first kinetic kill ASAT weapon was used more than a decade ago now. China has been practicing its latest BMD systems on hypersonic maneuverable vehicles. We're in a new era.
But BMD developments made the PLA aware of the need for increased ICBMs and warheads if we average each ICBM as carrying let's say 3 active warheads, PLA has known for over 40 years that the only sure way of countering proliferating and capable US BMD is by saturation and improved missiles. First part they need to build up more missiles to counter boost (if any) and mid course interceptors. So if the US have roughly 1000 interceptors positioned right around China's northern to southern directions, then China needs around 1000 ICBM ranged missiles as a minimum. That's 3x the no. of warheads so roughly 3000 warheads just for this task. The second part is developing much more advanced missiles and warheads and these eventually were revealed to be hypersonic vehicles using the Qian Xuesen type trajectories possibly with more complex flight patterns and shockwave riding air breathing or not. This is still a bare minimum to counter known minimum numbers of US interceptors.
Concurrent to this is a new and vast network of land, sea, and space based early warning with plenty of redundancy and of course various types of fire on command etc organisational and communication developments and how they are administered. The Chinese BMD is also up and running from the seldom talked about HQ and SC series we've only had hints of and tests of.
TLDR:
During the period between the 1980s and now, China knew it absolutely had to build up stockpile to the minimum 1000 warheads. Honestly the minimum is more like 1000 ICBMs and SLBMs but it's unknown if the CCP went to that secure an extent. They definitely have the desire now and doing it if it hasn't already been done. It also knew it had to field a considerable quantity of BMD interceptors which at the high end of threat can buy it time for retaliation strike or at the low end, neutralise North Korean or Indian missiles convincingly as a secondary function with the primary one being buying time to launch retaliation strikes where most of their arsenal could be protected for long enough to launch.
It did all this long ago while placating the US with "I only maintain about France and UK's stockpile numbers and have absolutely a no first use, minimum deterrence nuclear posture".
There is no way an equally big and much more promising and high potential economy with four times more people to defend and retaliate for in case, would ever allow their main adversary to be able to intercept their entire nuclear arsenal with just BMD on a single warship. This is impossible. It is also a cheap and easy matter, costing China less than 1% of GDP for every year for maybe just 10 years to build up to US levels. It's so bloody obvious it's a no brainer but liberal arts intellectual masturbators prefer complicating simple things with their desire for intellectual masturbation. The reality is so obvious, you can use logic only to determine China's true nuclear size to a decently accurate degree. This puts China's prior to more recent build up to around 1000 warheads with /3 no. of >DF-31A ranged missiles.
China's military strategy has always been deterrence first and then conventional build up. China has been building warships and aircraft at a rate that suggests all this extra conventional build up is left over from first meeting and exceeding "minimum nuclear deterrence". By logic we can and have ascertained to a decent accuracy that "minimum nuclear deterrence" for China since at least 2000s means able to deliver unacceptable levels of destruction on the US in case the US conducts a first strike which would disable a sizeable number of Chinese nuclear arsenal and then put roughly 1000 interceptors into the air in the Pacific for Canada/Arctic, and another 1000 at least around the continental USA then another 1000 at least of terminal phase interceptors.
