President Donald Trump sided with North Korea’s Kim Jong Un and continued to criticise former vice president and 2020 Democratic hopeful Joe Biden — this time on the world stage.

Trump said in response to a question at a joint news conference with the prime minister of Japan that Kim “made a statement that Joe Biden is a low IQ individual”. Trump said the assessment “probably is based on his record. I think I agree with him on that.”

Trump had been asked why he had appeared to side with a brutal autocrat instead of a former vice president.

There had long been a tradition of American leaders and candidates avoiding partisan talk on foreign soil.