Beijing has accused Washington of “excessive protectionism” after targeting imports of a key chemical from the United States. US President Donald Trump’s administration has brought a range of commerce cases against China. As trade tensions between the world’s two biggest economies rose again on Tuesday, China’s Ministry of Commerce said that Beijing “is concerned about the US’s serious trend towards trade protectionism in steel products.” More than half of the US's protective tariffs are related to steel, it added. The statement followed news late Monday that Beijing had taken aim at imports of a key chemical from the US, AFP said. The ministry said it had found dumping of styrene imports from the US, Taiwan and South Korea, in an initial ruling during a continuing trade investigation into the chemical.