China’s exports to developing markets have soared, opening indirect routes to the U.S. market that officials in Beijing worry may be closed under pressure from President Trump.

Trump cited the fentanyl issue as the reason for imposing a 10% tariff on all Chinese imports in early February, on top of any existing duties. He doubled that to 20% earlier this month. He also has cited fentanyl, along with other reasons, for imposing tariffs on Canada and Mexico.

Walmart is getting caught in the middle of an escalating trade war between the United States and China. Chinese officials confirmed on Thursday they had met with executives from the US retail giant, following a news report that it had pressured its suppliers in China for discounts to cope with rising tariffs imposed by Donald Trump.