President Trump has extended a self-imposed deadline on deciding whether to permanently exempt the European Union, Mexico and Canada from tariffs imposed by the U.S. on imported steel and aluminum, the White House announced Monday night. Mr. Trump had intended to announce his decision in a few hours, at midnight Tuesday. Now, the exemptions will remain in place for another 30 days.

The administration has also reached an agreement in principle with Argentina, Australia and Brazil.

"In all of these negotiations, the Administration is focused on quotas that will restrain imports, prevent transshipment, and protect the national security," the White House said in a statement.

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If the EU loses its exemption, it is threatening to retaliate with its own tariffs on U.S. goods imported to Europe. A possible trade war with Europe could come just as the Trump administration prepares for trade talks with China.

Mr. Trump decided in March to slap tariffs of 25 percent on imported steel and 10 percent on imported aluminum. He justified the action by saying it's needed to protect American metal producers from unfair competition and bolster national security. He had granted temporary exemptions to Canada, Mexico, Brazil, the European Union, Australia and Argentina.