US actions for one thing. See the history of how the US has blocked China's acquisition of those machines by simply applying pressure (not even threat of sancti

US actions for one thing. See the history of how the US has blocked China's acquisition of those machines by simply applying pressure (not even threat of sanctions) on Europeans. Also even you got your hands on them, you need a sufficient expertise and huge investments to build a fab. If you are part of the US block, then it's too expensive, if not, you can't buy, so you have to develop them yourself, which takes a lot of money and more importantly time. Even with all those money poured into this area, China plans to become self-sufficient on the chip front not earlier than 2030.