In April, Trump publicly promised that his trade war would result in "Made in America" iPhones, but Apple remained silent. By May, Trump appeared frustrated by Apple's supply chain moves, claiming while on a Middle East tour that he had “a little problem with Tim Cook."

Apple Chief Executive Tim Cook kicked off a plan to manufacture iPhones in India years ago. It was one of a series of savvy moves, along with a newly announced $100 billion U.S. investment, that have helped the company avoid President Trump’s recent tariff threats.

Apple made a big pledge at a White House event. But the logistics of creating a gadget like the iPhone, and managing its cost, are complex.