WASHINGTON (Reuters) - U.S. President Donald Trump reiterated on Tuesday his plan to slap big tariffs on imports of steel and aluminum, warning the European Union it would get hit with a “big tax” for not treating the United States well when it comes to trade.

U.S. President Donald Trump speaks during a joint news conference with Sweden's Prime Minister Stefan Lofven in the East Room of the White House in Washington, U.S., March 6, 2018. REUTERS/Leah Millis

“They make it almost impossible for us to do business with them and yet they send their cars and everything else back into the United States,” Trump said of the EU at a news conference with Swedish Prime Minister Stefan Lofven, whose country is an EU member.

Trump said the EU was taking advantage of the United States on trade, adding: “They can do whatever they’d like, but if they do that, then we put a big tax of 25 percent on their cars - and believe me they won’t be doing it very long.”

Trump said on Friday he would impose a duty of 25 percent on imported steel and 10 percent on aluminum, a plan that sparked cries of foul from U.S. trading partners and warnings from U.S. lawmakers and businesses of the potential for a tit-for-tat trade war that could hurt the U.S. economy.

Trump repeated his belief that the United States could win such a war, since it was running such a large trade deficit.

“When we’re behind on every single country, trade wars aren’t so bad,” he told reporters at the White House.

Lofven offered a warning of sorts to the U.S. president, saying: “I am convinced that increased tariffs hurt us all in the long run.”

Trump held out the prospect that close U.S. trading partners Canada and Mexico could avoid the steep tariffs if they reached a deal with the United States in the renegotiation of the North American Free Trade Agreement.

“But again, (with) other countries, we won’t have that choice. Unless they can do something for us,” he said, adding that the EU could find relief if it lowered barriers to U.S. products.

“Then we can start talking,” Trump said.