By Jacob M. Schlesinger, Emre Peker and Christina Rogers 

President Donald Trump repeated Friday his threat to slap stiff tariffs on European cars, hours after the European Union started imposing duties on a range of American products worth $3 billion in retaliation for separate Trump curbs imposed on steel and aluminum.

Mr. Trump's latest rhetorical broadside over trade indicates his desire to continue engaging in combat on multiple commercial fronts, moves that have roiled global markets in recent weeks. Earlier in the week, the president issued a statement saying he was widening his attack on Beijing, threatening to place tariffs on up to $450 billion of Chinese goods if the government retaliates for new duties on Chinese goods slated to take effect July 6.

"Based on the Tariffs and Trade Barriers long placed on the U.S. and it great companies and workers by the European Union, if these Tariffs and Barriers are not soon broken down and removed, we will be placing a 20% Tariff on all of their cars coming into the U.S. Build them here!" Mr. Trump wrote on Twitter Friday morning.

Following the tweet, shares in the big three German auto makers -- BMW AG, Daimler AG and Volkswagen AG -- were all down slightly in after-hours trading.

Mr. Trump's tweet suggests that, after picking trade fights with China over intellectual property, and a dozen countries over global metals overcapacity, he is now eager to move on to autos. The statement underscores the importance he is placing on a probe his administration launched last month into whether big tariffs could be imposed on vehicle imports in the name of national security.

No firm deadline has been set for that decision, but administration officials have suggested they are hoping to wrap up the process before the November U.S. elections.

Commerce Secretary Wilbur Ross, who is overseeing the auto investigation, told a Senate committee Wednesday that there "has been no decision made as to whether to recommend tariffs at all -- we're at the early stages in the process."

Mr. Trump's Friday tweet wasn't the first time he has threatened Europe with car tariffs, though the figure he cites has varied at times between 20% and 25%. He has regularly decried the disparity between the 2.5% tariff the U.S. currently charges for car imports and the 10% duty imposed by Europe. He doesn't mention that the U.S. imposes a 25% tariff on imports of light trucks, vs. Europe's 10% rate for those vehicles.

The tweet followed comments Mr. Trump made at Wednesday night's "Make America Great Again" rally in Minnesota, where he accused Europe of "basically saying 'we're going to sell you millions of cars, by the way, you're not going to sell us any.' " The president then added to cheers: "Not going to work that way anymore, folks. Not going to work that way."

European officials declined to respond to Mr. Trump's latest broadside. "Everything that we have to say on that subject has already been expressed...at various occasions over the last weeks," an EU official said Friday "We have nothing to add."

European officials are broadly exasperated with Mr. Trump's twitter announcements and threats, not all of which translate to actions but most of which stoke uncertainties and pressure fraying trans-Atlantic relations.

Top executives from the European Union's executive arm -- the European Commission -- have repeatedly called on Mr. Trump to negotiate with longstanding U.S. allies instead of raising trade barriers and seeking concessions with threats, such as levies on car exports from the bloc.

The commission's president, Jean-Claude Juncker, offered to visit Mr. Trump in Washington during the Group of Seven summit in Canada earlier this month, and the EU's Trade Commissioner Cecilia Malmstrom has reiterated this week Brussels's readiness to negotiate with the U.S. to address White House complaints.

Earlier this week, Germany's leading auto makers threw their support behind the abolition of all import tariffs for cars between the European Union and the U.S. in an effort to find a peaceful solution to the brewing trade war.

A White House spokeswoman didn't respond for a request to comment on what prompted Mr. Trump's tweet Friday.

The U.S. imported nearly 1.3 million vehicles last year from the European Union, representing about 7% of all light vehicles sold in the U.S. in 2017, according to forecasting firm LMC Automotive.

A 20% tariff would hit the German auto makers the hardest with BMW, Daimler and Volkswagen exporting a combined 726,300 vehicles to the U.S. last year, according to LMC. Fiat Chrysler Automobiles NV would be exposed, with it exporting roughly 154,400 vehicles to the U.S. in 2017.

A Volkswagen spokesman called the proposed tariffs a "tax" on the U.S. consumer that "will result in higher prices and also threaten job growth." He said the potential for escalating trade retaliation "presents a serious risk to economic growth in all countries."

A BMW spokesman said free trade is important for sustaining jobs in the U.S. A Daimler spokesman declined to comment.

"While we understand that the administration is working to achieve a level playing field, tariffs are not the right approach," said the Alliance of Automobile Manufacturers, a Washington-based lobby group that represents a dozen car companies. "Tariffs raise vehicle prices for our customers, limit consumer choice and invite retaliatory action by our trading partners."

--Adrienne Roberts contributed to this article.

Write to Jacob M. Schlesinger at jacob.schlesinger@wsj.com and Christina Rogers at christina.rogers@wsj.com

(END) Dow Jones Newswires

June 22, 2018 14:46 ET (18:46 GMT)