Heavy tariffs imposed by the administration of US president Donald Trump are likely to have a major impact across the globe, economists said, as they sought to assess the scale of the damage.

“The president effectively declared war on the world economy,” said Maurice Obstfeld, a former International Monetary Fund chief economist. “Retaliation can be expected, reinforcing the carnage.”

 Alan Blinder, former vice-chair of the Federal Reserve, tells Central Banking that if the tariffs persist or are