Prime Minister Justin Trudeau said Canada could use tariffs to fight any “increased pressure” of steel dumping into Canada aimed at circumventing new U.S. restrictions.

The tariffs Donald Trump unveiled last week could prompt steel to be shipped instead through Canada to skirt the levies, Trudeau said Tuesday at an ArcelorMittal Dofasco plant in Hamilton, Ontario. The prime minister is touring aluminum and steel production facilities, pledging support for workers after the U.S. president exempted Canada and Mexico from the protectionist measures.

“We are alert to that, we are working with partners in industry, with our American partners, to ensure that does not happen,” Trudeau said of so-called transshipment. “We have a whole suite of tariff and countervailing duties that are at our disposal to move forward and ensure that we are not accepting in unfairly produced or sold steel.”

The president’s decision last week exempted Canada and Mexico “at least at this time,” and called on the North American Free Trade Agreement partners to “take action to prevent transshipment” of aluminum and steel.

The prime minister said Canada has already implemented measures to stop transshipment, such as increased customs screening. Trudeau said some countries have lower labor and environmental standards—and while not specifically identifying them, he later criticized China and Russia.

“When we talk about these things, very often China is mentioned, there is also mention made of Russia,” he said, according to remarks translated from French by the Canadian Broadcasting Corp.

Canadian steel facilities can’t compete fairly against countries that choose “to sell at a loss in order to control the market,” he said. “We must be concerned by the actions that are being taken by the international community and understand that we simply cannot allow countries such as that to destroy our local industry.”