Washington (CNN) President Donald Trump escalated his threat to apply new tariffs on European autos Friday.

"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." he wrote on Twitter.

"Build them here!" he declared.

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! — Donald J. Trump (@realDonaldTrump) June 22, 2018

The threat came the same day the EU imposed new tariffs on American products, a retaliatory move for the tariffs Trump applied on steel and aluminum. The tweet sent shares of European automakers, including BMW and Volkswagen, lower.

Last month Trump instructed his Commerce Department to begin a national security investigation that would provide the legal underpinning for new tariffs on cars.

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