Propaganda. Some strategic rare earth is indeed rare.
As in economically extractable stuff are geologically rare.
The strategic heavy stuff (dysprosium, terbium, yttrium) for high performing magnets are ECONOMICALLY extracted from ionic clay deposits mostly in PRC, myanmar (controlled by PRC), and small pockets else where (Lynas Australia+Malaysia) which is <10% i.e. not enough for world demand but process still depends on PRC tech.
Rare earth is not rare for these HeavyREE in the sense that fresh water is not rare for a desert nation next to the ocean, you just have to spend $$$ desalinate. Except this is 2000s, and the technology to do so at scale doesn't exist. US+co would have to plow through order magnitude more rocks to get the small % of HREE, i.e it's much more energy intensive and polluting to the point where it might not even be strategically viable. See how PRC has MORE shale deposits than US on paper but they still have to import fossil because the shale is technically hard to access.
TLDR is PRC controls like ~90% of supply and ~100% of process for some strategic HREEs, i.e. more than US EUV tier control. The only saving grace is HREE doesn't depreciate like semiconductors so if it can be smuggled (like US did with Ti from USSR during coldwar) it would be golden, but you also can't rent HREE from the cloud. So it depends on how strong PRC enforces controls. The other reminder is there is host of other elements that are also strategic (Ga/Ge for radars etc), which PRC also functionally has 100% control over due to having ability to process to sigmas of purity, i.e. imagine if everyone has oil but only one country has refinery technology.
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.
Propaganda. Some strategic rare earth is indeed rare.
As in economically extractable stuff are geologically rare.
The strategic heavy stuff (dysprosium, terbium, yttrium) for high performing magnets are ECONOMICALLY extracted from ionic clay deposits mostly in PRC, myanmar (controlled by PRC), and small pockets else where (Lynas Australia+Malaysia) which is <10% i.e. not enough for world demand but process still depends on PRC tech.
Rare earth is not rare for these HeavyREE in the sense that fresh water is not rare for a desert nation next to the ocean, you just have to spend $$$ desalinate. Except this is 2000s, and the technology to do so at scale doesn't exist. US+co would have to plow through order magnitude more rocks to get the small % of HREE, i.e it's much more energy intensive and polluting to the point where it might not even be strategically viable. See how PRC has MORE shale deposits than US on paper but they still have to import fossil because the shale is technically hard to access.
TLDR is PRC controls like ~90% of supply and ~100% of process for some strategic HREEs, i.e. more than US EUV tier control. The only saving grace is HREE doesn't depreciate like semiconductors so if it can be smuggled (like US did with Ti from USSR during coldwar) it would be golden, but you also can't rent HREE from the cloud. So it depends on how strong PRC enforces controls. The other reminder is there is host of other elements that are also strategic (Ga/Ge for radars etc), which PRC also functionally has 100% control over due to having ability to process to sigmas of purity, i.e. imagine if everyone has oil but only one country has refinery technology.