Yep, and it's likely that China is the only place they could actually manufacture their products. China isn't the cheapest place to make things anymore, and it hasn't been in a long time - that's been supplanted by Bangladesh, Vietnam, etc. It's even within spitting distance to manufacture in the US.
Companies manufacture complex electronics products in China because everyone manufactures there. The skills are there, factories are there - but most importantly, the supply chains are there. You can drive a truck from factory to factory to pick up all the pieces you need. Then drop the truck off at Foxconn. They'll make the products and you can put them back into the truck and drop them off at the port or rail yard.
That's not something you can just replace overnight.