The United States has filed complaints against Canada and other countries at the World Trade Organization for retaliating against President Donald Trump’s tariffs on steel and aluminum.

Mr. Trump’s trade chief, Robert Lighthizer, announced five parallel WTO complaints Monday against Canada, the European Union, China, Mexico and Turkey – firing another salvo in a global trade war that has seen the U.S. target both its rivals and its closest allies.

In a statement, Mr. Lighthizer’s office claimed that Mr. Trump’s tariffs “are justified” but the retaliation of the other countries is “completely without justification.”

“The actions taken by the President are wholly legitimate and fully justified as a matter of U.S. law and international trade rules. Instead of working with us to address a common problem, some of our trading partners have elected to respond with retaliatory tariffs designed to punish American workers, farmers and companies,” Mr. Lighthizer said.

The Trump administration hit steel with tariffs of 25 per cent and aluminum with levies of 10 per cent. Canada responded with tariffs on U.S. steel, aluminum and a raft of consumer products from Kentucky bourbon to frozen pizzas to ketchup. The EU, China, Mexico and Turkey have similarly imposed retaliatory tariffs on American goods.

The U.S. cited “national security” as the reason for imposing its tariffs: Mr. Lighthizer claims that he has to keep foreign steel and aluminum out of the country in order to build up the U.S.’s domestic metal-making capacity so that it can make its own steel and aluminum in the event of a war. He argues that this justifies the tariffs under international rules, and contends that the other countries’ retaliation is illegal because they did not go through the WTO.

The Trump administration has sometimes undercut its own rationale for the tariffs – using the measures as a bargaining chip in NAFTA negotiations with Canada and Mexico, for instance. The talks stalled in May; Canadian officials have said they will resume at some point this summer, but have not set a date.

Canada has argued that the national security rationale was merely an excuse the Trump administration came up with to impose tariffs for reasons of pure protectionism.

The tariffs come as the Trump administration considers imposing tariffs of 25 per cent on all foreign-made cars and trucks – an even more devastating move that would cause hundreds of thousands of job losses.

The U.S. Commerce Department is holding a hearing Thursday to discuss the prospective tariffs, at which Canadian officials are expected to appear.

In a press release Monday, the new Ontario government of Doug Ford announced that Economic Development Minister Jim Wilson will address the hearing. Southern Ontario is the centre of Canada’s auto industry, with plants from American and overseas auto makers, numerous parts manufacturers and heavy integration with U.S. assemblies on the other side of the border.

“The U.S. and Ontario share a unique economic relationship grounded in fair and balanced trade, integrated supply chains and complementary markets,” Mr. Wilson said in a statement. “It is clear that Ontario is not a national security risk to the United States.”

The Globe and Mail, July 16, 2018