President Trump proclaimed Tuesday that “Tariffs are the greatest!” as he threatened new penalties ahead of what are likely to be hardball trade talks in Washington with European officials.

“Tariffs are the greatest! Either a country which has treated the United States unfairly on Trade negotiates a fair deal, or it gets hit with Tariffs. It’s as simple as that –and everybody’s talking! Remember, we are the ‘piggy bank’ that’s being robbed. All will be Great!” Trump tweeted early Tuesday.

Coming on the heels of Trump's contentious session with NATO allies earlier this month, European Commission President Jean-Claude Juncker is meeting with Trump on Wednesday to talk trade.

Trump has used the tariff threat as leverage to pursue new trade arrangements, and already angered European allies by imposing a 10 percent tariff on aluminum imports and 25 percent tariff on steel imports.

Trump now is threatening to put a 20 percent tariff on all European-made cars coming into the United States.

“Countries that have treated us unfairly on trade for years are all coming to Washington to negotiate. This should have taken place many years ago but, as the saying goes, better late than never!” Trump tweeted.

The president’s meeting with Juncker takes place two weeks after his NATO summit in Brussels, where Trump tangled with NATO allies over defense spending -- compounding tensions that already had risen over tariffs and trade.

Trump, in March, first announced the tariffs on steel and aluminum. They became effective in mid-March, with exclusions for Mexico, Canada, and the EU.

But in May, the Trump administration implemented the tariffs on allies, prompting retaliatory tariffs on U.S. goods. Last month, the EU began slapping tariffs on American imports like bourbon, peanut butter and orange juice.

A spokesman for the European Commission, part of the European Union, said on Monday that there would be “no offers,” and that the upcoming meeting is instead a “dialogue.”

“I do not wish to enter into a discussion about mandates, offers because there are no offers,” the spokesman said, according to Reuters. “This is a discussion, it is a dialogue and it is an opportunity to talk and to stay engaged in dialogue.”

Last month, Harley-Davidson also announced the company would move production of European-sold motorcycles abroad to avoid the increased tariffs imposed on American imports.

The Associated Press contributed to this report.