President Donald Trump's new tariff orders against Canada, Mexico and China all contain clauses suspending a duty-free exemption for low-value shipments below $800 that is widely seen as a loophole that has allowed shipments of fentanyl and its precursor chemicals into the United States.

The leaders of Mexico and Canada each said they had struck agreements to pause tariffs for 30 days, but levies on products from China were still set to take effect just after midnight.

The Canadian prime minister said the country has a $1.3 billion border plan and 10,000 "frontline personnel" protecting the border.