President Donald Trump said the sweeping tariffs that he has imposed on Mexico, Canada and China may cause "short term" pain for Americans as global markets reflected concerns the levies could undermine growth and reignite inflation.

This will be the golden age of America! Will there be some pain? Yes, maybe (and maybe not!). But we will make America great again, and it will all be worth the price that must be

Amid warnings of price increases, Canada moved quickly to retaliate, China said it had planned countermeasures and Mexico said it would soon unveil its response.