U.S. President Donald Trump threatened to impose a 20 per cent tariff on all European Union-assembled cars coming into the United States in a Tweet on Friday.

He said that the 20 per cent tariff is coming a month after the administration launched an investigation into whether auto imports pose a national security threat.

“If these Tariffs and Barriers are not soon broken down and removed, we will be placing a 20 per cent Tariff on all of their cars coming into the U.S. Build them here!’’ Trump wrote.

The U.S. Commerce Department aims to wrap up its investigation into whether imports of automobiles and auto parts pose a risk to national security by late July or August, Commerce Secretary Wilbur Ross said. (Reuters/NAN)