U.S. authorities are pressing ASML over suspicions that one of its most advanced EUV lithography machines may have made its way to China in violation of export controls.

ASML $ASML vehemently denies this — it says it has never delivered an EUV machine to China, that none are located there, and there are even documents circulating in Washington purportedly to prove that. We don't have a confirmed leak, but what we do have is nervous politics around the most sensitive piece of hardware on the planet. EUV is literally the only way to make the most advanced chips, and ASML is the only company on the planet that can build them — which is why any mention of China becomes immediately geopolitically explosive.