Washington DC — President Donald Trump declared Tuesday that “Tariffs are the greatest!” and threatened to impose additional penalties on U.S. trading partners as he prepared for negotiations with European officials at the White House.

Trump tweeted from the White House that U.S. trade partners need to either negotiate a “fair deal, or it gets hit with Tariffs. It’s as simple as that.”

The president has engaged in hard line trading negotiations with China, Canada and European nations, seeking to renegotiate trade agreements he says have undermined the nation’s manufacturing base and led to a wave of job losses in recent decades.

The imposition of punishing tariffs on imported goods has been a favored tactic by Trump, but it has prompted U.S. trading partners to retaliate, creating risks for the economy.

Trump has placed tariffs on imported steel and aluminum, saying they pose a threat to U.S. national security, an argument that allies such as the European Union and Canada reject.

He has also threatened to slap tariffs on imported cars, trucks and auto parts, potentially targeting imports that last year totaled $335 billion.