WASHINGTON (Reuters) - U.S. Commerce Secretary Howard Lutnick said nothing would stop President Donald Trump's expanded 25% tariffs on steel and aluminum until U.S. domestic production is strengthened, and that Trump will add copper to his trade protections.

Lutnick also told Fox Business Network that a meeting that he plans to hold with Ontario Premier Doug Ford will seek to "lower the temperature" between the U.S. and Canada, but he will wait for Mark Carney to be fully installed as Canadian prime minister to negotiate on trade on a national level.

"So I think it's just to level-set things, make sure we know each other, and then we're going to negotiate with all of Canada," Lutnick said on the meeting with Ford.

Lutnick said that steel and aluminum were among essential products that must be made in the United States for national security reasons, along with semiconductors and pharmaceuticals.

"We can't be in a war and rely on steel and aluminum from some other country. I mean, it's just not reasonable," Lutnick said. "So the president wants steel and aluminum in America, and let me be clear, nothing is going to stop that until we've got a big, strong domestic steel and aluminum capability. And by the way, he's going to add copper to that mix too."

Trump in late February ordered Lutnick to conduct a Section 232 national security investigation to determine whether to levy tariffs on copper imports, using the same law that backed the steel and aluminum duties.