And you don’t think that China could have obtained that technology?
Not for such products.
Manufacturing is not like programming, where if you steal the code you can duplicate it.
There is a lot of know how in the physical process that can’t just be duplicated through book knowledge, you either need training by a person who has the known how, or you need many years of experimentation and trial and error until you get it (and there is still a chance you don’t ever get it right).
It like if someone stole the recipe from a famous chef, it doesn’t mean he’ll start making Michelin level gourmet dishes right away.