This post really demonstrates ignorance of the supply chain. Electronics are manufactured in China and the surrounding region because that’s where all the third party suppliers are. Apple isn’t going to recreate a trillion dollar network of third party suppliers in the United States.
It’s like saying: start a seafood restaurant in the Sahara desert. Not only would you have to import all the fish, you’d have to create manufacturers for plates, cups, cutlery, napkins, salt, a farm for the ingredients, you’d need to mine your own natural gas to run your stove... and so on. You’re saying: JUST OPERATE A RESTAURANT IN THE SAHARA! JUST DO IT! I DON’T CARE ABOUT THE DETAILS. But the details are important. You might be able to imagine how expensive it would get to operate that restaurant. Nobody could afford to eat there.
Apple doesn’t make iPhones and Macs in a vacuum. There are dozens of individual suppliers who have their own suppliers who may also have their own suppliers. That infrastructure doesn’t exist in the United States. Recreating it isn’t feasible and neither is it Apple’s job to do it. If Trump wants the United States to rival China in manufacturing, then he should create the policies and investments needed to build that industry in the US. But he’s not sophisticated enough to even understand that, let alone implement it.
I completely understand your point as it would relate to say the iPhone but this is about the Mac Pro - a relatively low volume product. They manufactured the nMP 6,1 in one of Flextronics' (well I guess they've officially rebranded as Flex these days) US based facility (I think it was the Round Rock plant). Flex has significant contract manufacturing capacity for this sort of device in the US already. There isn't a lack of infrastructure to make that happen. It's a financial decision, I'm not saying it's the wrong decision but it is financial in nature and not based upon feasibility.