US President Donald Trump repeated threats to impose 25 percent tariffs on imports from Canada and Mexico starting Saturday.

Speaking to reporters at the White House on Thursday, Trump said crimes and illegal drugs are flowing into the United States from the two neighbors at unprecedented levels. He also noted that the US has huge trade deficits.

Trump said the tariffs "may or may not rise with time." He apparently expects to use tariffs as a bargaining chip to achieve concessions from other countries.

His nominee for Commerce Secretary, Howard Lutnick, has also indicated that Canada and Mexico will be able to avoid tariffs if they act swiftly.

Also on Thursday, Trump warned in a social media post that China, Russia and other emerging economies known as BRICS countries will face tariffs if they move to undermine the dollar's role as a global currency.

He wrote, "We are going to require a commitment from these seemingly hostile Countries that they will neither create a new BRICS Currency, nor back any other Currency to replace the mighty U.S. Dollar, or they will face 100% Tariffs, and should expect to say goodbye to selling into the wonderful U.S. Economy."