The European Union filed a complaint with the world trade organization on Monday asking the United States to lift tariffs on imported metals imposed by President trump, in one of the highest-profile and most contentious cases facing the WTO.

Trump imposed tariffs of 25 percent on imported steel and 10 percent on aluminum in 2018. He is relying on a 1962 us law that allows Mr Trump to restrict imports on national security grounds.

The U.S. move prompted nine WTO complaints from steel exporters, including China, India, Russia and Turkey. Canada and Mexico have dropped their lawsuits after reaching an agreement with the United States on a new free trade agreement.

European Union and U.S. officials presented their arguments to a three-member panel on Monday. The panel consists of three arbitrators from Uruguay, Chile and the Philippines. The case centres on the "national security exception" clause, which allows members to breach WTO obligations on the grounds of "national security".

America's central argument is that national security should be judged by countries themselves, not by a three-member WTO panel in Geneva. "If the us loses, trump will be very angry," said a diplomat from one of the complainants. The WTO panel, which handles all seven cases, has said it will not rule until the fourth quarter of 2020, so a decision may come after the November 3 U.S. presidential election.

Eu legal adviser James Flett said the case was dramatic but also "straightforward" and that the us tariffs were aimed at "making America rich again" rather than protecting its security. These measures are also a form of "defence measures" that, under WTO rules, should only apply if imports increase.

The us legal team said the eu had previously argued that national security was a matter of "self-judgment" and that the us had imposed sanctions on it during the falkland islands war of the 1980s and the nicaraguan civil strife. "To be honest, the eu's shift in position is a mystery," said one American lawyer. (From LGMI)