SAULT STE. MARIE, Ont. - Prime Minister Justin Trudeau will be in Sault Ste. Marie, Ont., and Regina today as he continues a tour of steel and aluminum plants to reassure workers there are measures in place to shield them from the possibility of U.S. tariffs.

U.S. President Donald Trump recently exempted Canada and Mexico from tariffs of 25 per cent on steel and 10 per cent on aluminum, although the U.S. government has been dropping hints that the exception is only temporary.

During his earlier visits to factories in Saguenay, Que., and Hamilton, Trudeau said the national security argument the U.S. has made when it comes to considering tariffs makes no sense and could not apply to Canada.

Speaking in Hamilton on Tuesday, Trudeau said there are measures in place, including tariffs and tougher border controls, to prevent steel and aluminum producers in other countries from using Canada as a back door to slip cheap metal into the United States.

Trudeau said the surplus of steel in the global market is not new and with American tariffs in place, some countries might try to ship their products to the U.S. through Canada.

He said Canada would be alert to that and work with industry partners and the United States to make sure that doesn't happen.