"The European Union and Canada have requested WTO dispute consultations with the United States regarding US duties on certain imported steel and aluminium products. The requests were circulated to WTO members on 6 June," the WTO said in a statement.

The text of a complaint is only made public after the WTO circulates it to its members.

ADVERTISEMENT In separate filings with the WTO, the EU and Canada claim that the tariffs violate the international organization's 1994 General Agreement on Tariffs and Trade as well as its Agreement on Safeguards.

Trump moved June 1 to remove exceptions for tariffs of 25 percent on imported steel and 10 percent on aluminum from the EU, Canada and Mexico, citing national security concerns for the steel and aluminum industries.

The countries dispute that rationale in their claims filed with the WTO, accusing the U.S. of imposing the tariffs “for reasons related to economic welfare and other factors that are not necessary for the protection of its essential security interests.”

Earlier Wednesday , the EU said it was preparing to impose a host of retaliatory tariffs against the U.S. starting in July.

“The Commission expects to conclude the relevant procedure in coordination with member states before the end of June so that the new duties start applying in July,” European Commission Vice-President Maros Sefcovic told a news conference

The tariffs will target some $3.3 billion worth of U.S. exports, including agricultural products and iconic American items such as bourbon, motorcycles and blue jeans.

Canada and Mexico have also responded with retaliatory tariffs.

Should the WTO rule that Trump’s tariffs are illegal, the EU is planning to impose another $4.2 billion in tariffs on American goods, though those would not take effect until 2021.

Critics of Trump’s tariffs have warned that his aggressive trade actions could spark a trade war, in which the U.S. and its trade partners volleyed tariffs back and forth, hurting exporters and consumers.