The United States is taking the fight over steel and aluminum tariffs to the World Trade Organization, arguing retaliatory trade actions launched by Canada, China, the European Union, Mexico and Turkey violate WTO rules.

“The actions taken by [U.S. President Trump] are wholly legitimate and fully justified as a matter of U.S. law and international trade rules,” said U.S. Trade Representative Robert Lighthizer in a release. “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.”

“The United States will take all necessary actions to protect our interests, and we urge our trading partners to work constructively with us on the problems created by massive and persistent excess capacity in the steel and aluminum sectors.”

The U.S. imposed the so-called Section 232 tariffs earlier this year on national security grounds, though the White House did grant temporary reprieves for a number of countries including Canada, pending the conclusion of NAFTA negotiations. After talks hit an impasse, the U.S. imposed 25-per cent tariffs on Canadian steel and 10-per cent duties on aluminum, effective July 1, ratcheting up the tension on the trade file.

Canada responded in kind, imposing surtaxes on $16.6-billion worth of U.S. steel, aluminum and consumer goods, including inflatable boats, ballpoint pens and gherkins.