(say Iran oil is cut from China, it has shown how it can `lockdown`, more ru oil, And imagine China bans export of food to US

This economic WWIII doomsday scenario would imply lockdown of non-essential vehicle travel, would still have essential manufacturing going on, more planned economy and state intervention, meanwhile if needed the ban on export of food and other products to US and Europe (if it would join US), would devastate businesses in US and “national security“, coupled with potential total ban of Russian oil to Western market, you probably get an answer if you actually can just harmlessly sanction China (along with the whole Asia, and the whole world in fact). Politicians and unashamed greedy entrepreneurs would of course kinda get an excuse but “At What Cost“ (as western journalist like to say)?) (the unrest in the West would probably be also Quite spectacular, as we’ve seen “even“ with Palestine) And obviously you can’t do anything militarily to China being the initiator of actual WWIII.