Donald Trump has dropped the broadest possible hint that he is ready to dig in for the long term in the Washington’s trade war with China, after the latest escalation in the long-running dispute between the world’s two largest economies.

The US president said he was ready to provide support for US farmers in 2020 should they face pressure from China, as economists at Goldman Sachs said the standoff could continue until after the US presidential election in November 2020.