How expensive matters, can stop NK and RU from access/buying in quantities that effects planning. And we're talking about a lot of commodity tier globally diffused/produced components where there are many sources and enforcement is really US weaponing the dollars. Different from PRC having production monopoly over critical input for high temperature magnets that say a F35 or AIM120 component needs but have no alternate supply chains for. It's not COTs stuff like chips from washing machines used for a lowend drone.

Just like EUV block, it's really matter of how much buying such things (in quantities required) gets disrupted, i.e. enough to degrade supply chain enough that force US to make expensive / different choices, waste 100s of billions and decades to retool MIC away PRC HREE. PRC has less highend compute for training than it would otherwise have without EUV block, and US can likely have less high-end hulls, airframes, less performent munitions and sensors etc... amount of access ripples across strategic landscape.

All current US+co HREE for some strategic elements touch PRC supply chains. And TBH PRC can probably execute export controls much more effectively than US, but these are PRC's first legislated, structured global export controls from PRC. So hard to say how effective it will be, but they may very well be able to stop US+co more than US+co can stop NK or RU.

PRC can go full nuclear, functionally 100% some strategic HREE components to be produced in PRC. Like how US wants 50% highend semi produced in CONUS, but with semi, US is only one key chokehold supplier and has to negotiate with multiple parties, PRC can solely control HREE that's concentrated in PRC for short/medium term. Again that translates to US not able to build up platforms&stockpiles in sufficient #s, or spend $100Bs and critically, more time to design around shortage. Next thing you know, short/medium term procurement changes enough entire force / deterence balance breaks.

You can't stop north korea/russia buying from the capitalist west (How do Russia get over a billion dollars worth of serialized/tracked aircraft parts to replenish their fleet this year? How do serialized/batch tracked parts end up underground when you track which airplane every part goes into?). It might be different for China, where instead of politicians/government people overlooking loopholes (because money must flow) China executes people for not following the rules.

Yeah, its really hard to track equipment electronic parts

imagine tracking sand, thats what china really trying to do buddy