Following a flurry of charges and countercharges, the World Trade Organization said Wednesday it would probe whether the U.S.' steel and aluminum tariffs were legal, a decision the Trump administration has indicated that it may use to challenge the legitimacy of the body. The U.S., meanwhile, has pushed the WTO to investigate China's allegedly predatory trade policies and acted to defend its tariffs as needed to defend domestic industries.

The European Union, China, Canada, Mexico, Norway, and Russia asked the WTO to conduct a probe, arguing the Trump administration's claim that its tariffs were necessary for national security reasons is bogus. The White House has argued the tariffs serve to protect domestic industries, which are in turn necessary to supply the U.S. military.

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“Some [WTO] members have expressed concerns that invoking the national security exception in these circumstances would undermine the international trading system," U.S. Ambassador Dennis Shea said, according to Reuters. "This is erroneous, and completely backwards."

The American delegation also said that challenging the White House's position “would undermine the legitimacy of the WTO’s dispute settlement system and even the viability of the WTO as a whole,” according to a report by Bloomberg.

The U.S. on Wednesday challenged retaliatory trade measures against its tariffs by Canada, Mexico, China and the EU. The U.S. argued the countries were "pretending to follow [WTO] rules while imposing measures that blatantly disregard them." A Chinese official said the U.S. statement "reeks of hypocrisy."

An administration spokesman could not be reached for comment.