Stocks in the U.S. declined on Wednesday after Donald Trump implied he wanted to impose new tariffs on China. Doing so could increase the costs and hurt overseas sales for U.S. manufacturers such as Boeing. A White House spokeswoman said that the president is pressing China to “reduce Beijing’s bilateral trade surplus by $100 billion.” After setting new solar panel tariffs earlier this year, Donald Trump now plans to impose additional tariffs on metal imports into the U.S.Trump is looking to levy tariffs on up to $60 billion of Chinese imports, targeting the technology, telecom and apparel sectors, sources told Reuters on Tuesday. According to Michael O’Rourke, chief market strategist at JonesTrading, a trade war is going on right now. Investors have acted quickly by taking profit amidst the uncertainty around potential trade barriers. The Dow Jones Industrial Average fell 249 points or 1% after the market close.

A major component of the Dow index is the aerospace company Boeing. Unlike tech companies such as Amazon which barely makes a profit and has thin profit margins, large manufacturing companies using hard commodities such as Boeing Co (NYSE:BA) do typically show growing earnings over time. Boeing shares have spiked in value during Trump’s presidency so far. The stock has accounted for about 400 points, or 29%, of the Dow’s 1,431-point gain in January. Over the past year it has gained about 85%.

However things started to change at the start of this month. According to Market Watch, shares of Boeing Co. fell by 2.5% on Wednesday “to suffer a third-straight loss, putting them on track for their biggest weekly decline in over two years, as concerns over the potential negative effects of President Donald Trump’s tariff plan continued to weigh on the aerospace and defense giant. Boeing’s stock BA.” Since its record close in February, Boeing’s stock has slumped 9.4%. Boeing not only makes commercial airplanes, but it also creates military aircrafts and network and space systems. Its military segment is engaged in the research, development, production and modification of manned and unmanned military aircraft and weapons systems