Hit by US tariffs and the blacklisting of Chinese telecoms equipment supplier Huawei, Beijing recently found a way to send a threatening trade message - with a visit by Chinese President Xi Jinping to a rare earth processing plant.

An editorial in the official People's Daily newspaper on the subject warned: "Don't underestimate China's ability to strike back." The newspaper even used a phrase - translated as "don't say we didn't warn you" - previously employed just before border wars with India and Vietnam.