Many US-branded products like Apple's are manufactured in China. Are these products considered Chinese when they are imported back to US? And are they thus subject to tariffs?
Short answer, yes, they are considered Chinese imports. Your excellent question speaks to the flaw in using Gross Domestic Product as a measurement of the health of a nation's economy.
The flaw is that the simplistic assignment of "import" and "export" completely misses the reality of modern manufacture and trade, where parts come from multiple nations.
If trade numbers more accurately accounted for how products are made, it is possible that the United States would not have any trade deficit at all with China. The problem, in short, is that trade figures are currently calculated based on the assumption that each product has a single country of origin and that the declared value of that product goes to that country. Thus, every time an iPhone or an iPad rolls off the factory floors of Foxconn (Apple’s main contractor in China) and travels to the port of Long Beach, California, it is counted as an import from China.