"The U.S. measures are a protectionist intervention in international trade and run counter to the principles of the WTO (World Trade Organization)," Wirtschaftsvereinigung Stahl said in a statement on Thursday.

"The U.S. allegation that EU imports are a threat to national security is grotesque," it added, calling for a swift WTO decision on challenges to the tariffs.

(Reporting by Maria Sheahan; Editing by Edward Taylor)