By Jarrett Renshaw, Daphne Psaledakis and David Lawder WASHINGTON (Reuters) - President Donald Trump said on Sunday 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.

Canada and Mexico ordered retaliatory tariffs on American goods in response to sweeping tariffs imposed by President Donald Trump, and businesses and consumers in both countries questioned Sunday how the new trade war might affect them.

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.