BERLIN — The eight European countries targeted by U.S. President Donald Trump for a 10% tariff for opposing American control of Greenland blasted the move Sunday, warning that his threats “undermine transatlantic relations and risk a dangerous downward spiral.”

The joint statement by some of America’s closest allies signaled a possible turning point in the recent tensions over sovereignty and security nearly 24 hours after Trump’s threat.

It was also the most forceful rebuke of Trump from the European allies since he returned to the White House almost a year ago. In recent months, Europeans have mostly opted for diplomacy and flattery around him, even when seeking an end to the war in Ukraine. Sunday’s statement, as well as some European countries sending troops to Greenland for a Danish military training exercise, appeared to be a step away from that strategy.

The unusually strong joint statement from Denmark, Norway, Sweden, France, Germany, the United Kingdom, the Netherlands and Finland said troops sent to Greenland for operation “Arctic Endurance” pose “no threat to anyone.”

Danish Foreign Minister Lars Lokke Rasmussen told reporters in Oslo that a dialogue was opened with the U.S. last week and “we will not give up on that. … So we will stay on track — unless U.S. decides differently.”

Added Norwegian Foreign Minister Espen Barth Eide at the same news conference: “We will not allow ourselves to be put under pressure, and those types of threats (of U.S. tariffs) are unacceptable between close allies,”

EU Council President Antonio Costa said Sunday the bloc’s leaders agree “that tariffs would undermine transatlantic relations and are incompatible with the EU-U.S. trade agreement.”

Trump’s Saturday announcement sets up a potentially dangerous test of U.S. partnerships in Europe. He appeared to indicate that he was using the tariffs as leverage to force talks over the status of Greenland, a semiautonomous territory of NATO ally Denmark that he regards as critical to U.S. national security.

“We stand in full solidarity with the Kingdom of Denmark and the people of Greenland,” the group said. “Building on the process begun last week, we stand ready to engage in a dialogue based on the principles of sovereignty and territorial integrity that we stand firmly behind. Tariff threats undermine transatlantic relations and risk a dangerous downward spiral.”

There are immediate questions about how the White House could implement tariffs against the EU. It was unclear, too, how Trump could act under U.S. law, though he could cite emergency economic powers that are currently subject to a U.S. Supreme Court challenge.