The US has successfully stopped them from acquiring the machines. That's not the same as stopping them from acquiring the capability to make them. On the contrary.
ASML of the Netherlands agreed to go along with past US requests to not supply China with bleeding edge machines, so China is making do with the older models while working hard to break the non-US hardware monopoly.
Washington, via the recent MATCH Act, has requested ASML to not supply or maintain any of the older equipment.
ASML has travelled to Washington to tell US Congress to take a long walk off a short pier.