Apple built its empire with China. Now its foundation is showing cracks

Every September, Apple unveils its latest phones at its futuristic Silicon Valley campus. A few weeks later, tens of millions of its newest handsets, assembled by legions of seasonal workers hired by its suppliers, are shipped from Chinese factories to customers around the world.

The annual release of Apple’s iPhones usually runs like clockwork, a prime example of how the U.S. tech giant has become the most profitable company of the globalization era by seamlessly navigating the world’s two largest economies.