The World Trade Organization (WTO) has found that tariffs on steel and aluminum imports that were imposed by the U.S. under former President Donald Trump violate global trade rules.

Trump had claimed national security concerns when he announced the new border taxes in 2018, sparking a wave of trade fights around the world.

BBC News reports that the WTO rebuffed that argument, saying the duties did not come "at a time of war or other emergency." The U.S. said it stood by the tariffs.

The U.S. "strongly rejects" the ruling and has no intention of removing the measures, assistant U.S. trade representative Adam Hodge said.

"The Biden administration is committed to preserving U.S. national security by ensuring the long-term viability of our steel and aluminum industries," he said, adding that the reports "only reinforce the need to fundamentally reform the WTO dispute settlement system".

The cases were brought by China, Norway, Switzerland and Turkey.

The WTO said the U.S. should bring its trade policy into compliance. If the country does not abide by the decision, the countries who brought the complaints are entitled, under WTO rules, to impose retaliatory tariffs on the U.S.

The U.S. can also appeal. That would leave the dispute in limbo because the U.S. has for years blocked appointments to the WTO's appellate body, which hears appeals, leaving it unable to function.