China has threatened retaliation after the Trump administration received a green light to impose steep tariffs on aluminium and steel imports on national security grounds, in the latest escalation of trade tension between the world’s top two economies.

US commerce secretary Wilbur Ross on Friday recommended a possible global tariff of at least 24 per cent on imports of steel and 7.7 per cent on aluminium after investigations into trade in both metals determined that import surges seen in recent years “threaten to impair our national security”. 

Wang Hejun, an official at China’s commerce ministry said imposing tariffs on such grounds was reckless. “The spectrum of national security is very broad and without a clear definition it could easily be abused,” he said.