"From the EU point of view, the US administration violates existing WTO rules in this case," Zypries said in a letter to her US counterpart Wilbur Ross, as quoted by the Redaktionsnetzwerk Deutschland media group.
The minister emphasized that the US move could have negative consequences for global trade and the European Union could respond to the decision of Washington.
The statement follows the March 1 Trump's decision to impose a 25-percent tariff on US imports of steel and a 10-percent tariff on aluminum for an indefinite period of time.
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A number of countries have expressed concerns over Trump's statement, with some of them stressing the need to respond with retaliatory measures.
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