No need to switch to the war economy if the Chinese government starts to build them now. If one of the defense companies set up the supply chain and an automatic assembly line that can produce ten thousand cheap long range piston-base missiles (minus the warhead to make storing them easier) per month, PLA will have hundreds of thousands of them in a few years. PLA can store them in any cheap warehouse because they don’t have explosive warheads.
PLA can maintain maybe ten thousand warheads and place them in munition storage facilities.
Maybe a year or so before the breakout, PLA can start to increase the missile production and really scale up the production of warheads. By the time hostilities starts, PLA will have enough missiles to turn South Korea, Japan, Taiwan Island and the Philippines back to stone ages.
This, I believe, is the core reason why the US is so paranoid about China providing lethal assistance to Russia.
It’s pretty obvious by now that one of the original wet dream core objectives behind the whole Ukraine idiocy from Washington’s POV was to essentially do start transitioning the US to war economy in stealth, under the guise of military assistance to Ukraine to attempt to not trip too many alarm bells in Beijing.
Russia was supposed to crumble and fold, but not before the war hogties they EU to America’s boot and forces them to modernise their own armed forces (preferably with newly built American gear). So after a few years of Slavics killing each other by the thousands, Russia is supposed to be exhausted and/or regime changed and effectively off the board, allowing the US and their newly refreshed European allies to focus building a NATO of Asia (which can now be supplied by a rejuvenated American war economy capable of producing vast amounts of weapons and munitions) to focus fire on China.
Reality is going a little differently to say the least, and the most hilarious part is China managed to checkmate this entire elaborate plan with one simple move - export control on gallium. What good is a vast new production base if you don’t have the core raw ingredients to feed into it?
Notice China’s shrewd planning and patience in the timing. It didn’t knee-jerk the move immediately, it patiently waited a year for the US to deplete significant proportions of its munitions supply and invest heavily in new manufacturing capacities before pulling the rug out from under it all after all those costs have been sunk and resources expended. I would not be at all surprised if China deliberately slowed (but not stopped to avoid tipping them off) deliveries of gallium shipments to the US while also accepting massive orders to get the US to run down its gallium strategic reserves before the export control announcement. The reason western arms manufacturers are so panicked might well be because the shipment date for the vast gallium orders they placed and is counting on is due to start shortly after the export controls are due to come into force.
China has already been doing war prep by increasing production of key dual use components and vastly increasing the export of such dual use items to Russia. This is actually the most difficult and time consuming part of boosting production for wartime surges because these chips and sensors are very complex and require significant investment in time, money and human capital to bring new production capabilities online. Classic example is a chip foundry that costs billions and years to build, and require very specific tools and machines that the west is desperately trying to keep a stranglehold on, but which China is systematically breaking out of.
However, it is entirely possible that China is ready to turn up the heat on the west in Ukraine now. Notice how so many of the weapons they North Koreans showcased to Shoigu recently looked uncannily like systems the PLA are using? China can truthfully say they are not providing lethal assistance to Russia if North Korea sells Russia the weapons, even if North Korea imports 99% of the core key components from China and just swaps the Chinese labels for Korean ones and does final assembly, just like how carbon China emits manufacturing goods for western companies to be sold to western consumers don’t count as carbon emitted by western countries.