Tesla (TSLA. O) has warned that U.S. President Donald Trump's trade war could make it the target of retaliatory tariffs against the United States and increase the cost of building cars in the United States, according to the Financial Times. In an unsigned letter to U.S. Trade Representative Jamison Greer, Tesla said it "supports" fair trade, but warned that "U.S. exporters will be disproportionately affected when other countries respond to U.S. trade actions". "Past U.S. trade actions, for example, would result in immediate responses from targeted countries, including increased tariffs on electric vehicles imported into those countries," the company wrote in its March 11 letter. The letter emphasizes that even Tesla, led by Musk, a close Trump ally, is concerned about the potential impact of broad tariffs.