Or could Americans just not manufacture Apple products?

The fact that this is even a question (that I also don't know the answer to) is indicative to me that we should find out. Being wholly reliant on a foreign nation for something as ubiquitous as chips should be seen as a potential security risk. Not in a handwavy 'privacy' context, but in one that it severely limits options should there be a disagreement.

Of course it is possible. It would take some time and money, but if Apple wanted to do it they could. There are plenty of places that could use good jobs and have manufacturing experience like the Appalachia region.

I think something else is up with Apple not wanting to do production in the Americas

This is why the whole history of, say, Europe involves almost no wars between neighbors with large amounts of trade just before the war, right?

Furniture is an example where we should care much less.

Even without government intervention, a good CEO should know better than to put all of his company's eggs in one basket, whether that's an individual nation, or a single parts supplier.

Apple's massive growth in services would somewhat insulate it from a locked-out-of-China scenario. At least long enough to establish diverse manufacturing elsewhere.

As an Apple shareholder, for years I've been repeatedly disappointed with Mr. Cook's swooning and fawning over China. Not just for political and social reasons, but because he put the company and its future in jeopardy chasing Chinese manufacturing trends for short-term dollars. I want a CEO with long-term vision, who makes the company resilient so it'll keep producing revenue longer than the next three months.

Do you think Apple is allowed to manufacture in Iran? The government is already telling companies where they can or cannot manufacture.

(And yes, that means that other countries in which a multinational has operations can do the same thing. If you look at China--they already do.)