Mexico supplanted China as the No. 1 trading partner of the U.S. in August.
The U.S. and China have only completed the first phase of their trade deal that brought their tariff battle to a standstill.
"Over the last 20 years, American investors alone have invested $100 billion worth in China, most of that in manufacturing," Heritage Foundation policy analyst Riley Walters, who focuses on Asian economies and tech, told FOX Business. "Over the years, U.S. investment has shifted types. U.S. investors are also looking now to higher-end goods because that's the demand for U.S. consumers, global consumers."
"It's not just a shift in what China can do, it's what U.S. investors are asking China to do," Walters said.
Meanwhile, the majority of China's imports come from other Asian countries, although the U.S. sold $133 billion worth of goods to China, according to 2017 data from the Observatory of Economic Complexity, a Massachusetts Institute of Technology-linked trade tracker.
The trade imbalance between the U.S. and China partially motivated the Trump administration's trade war.
"Officially, it's intellectual property theft," Walters said. "It's the concern that either Chinese companies or government officials will coerce or demand American companies operating in China to transfer secrets. ... Unofficially, it's the trade deficit the U.S. has with China. I think this is the big concern for this administration."
FOX Business' Megan Henney contributed to this report.