Washington (CNN Business) American sneaker company New Balance welcomed President Donald Trump's tough trade stance in 2016 -- but now the athletic footwear manufacturer is strongly opposing the President's latest threat to expand tariffs on China.

New Balance boasts that it's the only major company to make more than four million pairs of athletic shoes a year domestically. It has five New England factories, with one more expected to open next year. The catch? It needs to import component parts from China that are no longer made in the United States.

"The proposed Tranche 4 tariffs will risk our company's overall financial health, which will in turn limit our ability to maintain and reinvest in our American factories," said a letter submitted by New Balance to the US Trade Representative's Office ahead of a hearing next week.

It's just one example of how many American corporations have built supply chains that span the globe, and why Trump's protectionist trade policies won't work to bring manufacturing back to the United States. It's just too hard to ding China without hurting American companies, workers and consumers along the way.

New Balance will join a chorus of opposition to a proposed new round of tariffs on Chinese goods at hearings this week. More than 300 company executives and trade group officials are scheduled to testify, from industries ranging from apparel and toys to fishing and fireworks.