In the final days of his presidency Barack Obama opened a trade case against China that was meant as a capstone to his administration’s economic battles with Beijing.

The litigation brought at the World Trade Organization was nominally against illegal subsidies Beijing used to help its aluminium industry, however US officials who had spent more than year working on it saw it as something bigger. They were launching a guided missile at the financial infrastructure of China’s state-directed economy.

Announcing the case, Mr Obama pointed to the low-interest state bank loans, cheap electricity and other government subsidies that China had used to fuel a “global glut” in aluminium and steel. All were illegal, he argued, and all were causing pain for China’s competitors internationally.