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.

Apple has outlined its plans for the 100 billion dollar investment in both materials and labor sourced in the U.S., including producing 100% of iPhone and Apple Watch displays in Kentucky.

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.