European Union leaders on Saturday warned of a "dangerous downward spiral" over President Donald Trump's vow to implement increasing tariffs on European allies until the U.S. is allowed to buy Greenland.

"Tariffs would undermine transatlantic relations and risk a dangerous downward spiral. Europe will remain united, coordinated, and committed to upholding its sovereignty," European Commission President Ursula von der Leyen and EU Council President Antonio Costa said in posts on X.

The bloc's top diplomat Kaja Kallas said tariffs would hurt prosperity on both sides of the Atlantic, while distracting the EU from its "core task" of ending Russia's war in Ukraine.

"China and Russia must be having ⁠a field day. They ​are the ones who benefit from divisions among allies," Kallas said on X.

"Tariffs risk making Europe and the United States poorer and undermine our shared prosperity. If Greenland’s security is at risk, we can address this inside NATO."

Ambassadors from ⁠the ​European Union's 27 countries will convene Sunday for an emergency meeting to discuss their response to the tariff threat.