President Trump on Saturday escalated a diplomatic standoff with NATO allies, announcing that he intends to impose a new 10 percent import tax on goods from eight European nations starting in February. 

The tariff, which presumably would be on top of the existing 15-percent tariff on imports from the European Union, are being described as retaliation for European opposition to the United States’ proposed acquisition of Greenland.

In a post on Truth Social, the president targeted Denmark, Norway, Sweden, France, Germany, the United Kingdom, the Netherlands, and Finland. He issued an ultimatum, saying that the added tariff would climb to 25 percent on June 1 if a deal is not in place for “the Complete and Total purchase of Greenland” by the United States.

“We have subsidized Denmark, and all of the Countries of the European Union, and others, for many years by not charging them Tariffs, or any other forms of remuneration. Now, after Centuries, it is time for Denmark to give back — World Peace is at stake!” the president wrote.

“China and Russia want Greenland, and there is not a thing that Denmark can do about it. They currently have two dogsleds as protection, one added recently,” he wrote.

“Nobody will touch this sacred piece of Land, especially since the National Security of the United States, and the World at large, is at stake. On top of everything else, Denmark, Norway, Sweden, France, Germany, The United Kingdom, The Netherlands, and Finland have journeyed to Greenland, for purposes unknown. This is a very dangerous situation for the Safety, Security, and Survival of our Planet,” Mr. Trump wrote.

The threat marks a significant strain on the NATO alliance, which has provided collective security to Europe and North America since 1949. While it remains unclear under what authority he would impost the new tariffs, the president could cite economic emergency powers currently under review by the U.S. Supreme Court.

Mr. Trump said that the tariffs were a response to recent visits to Greenland by representatives from Britain, the Netherlands, and Finland, as well as general resistance to his efforts to purchase the semi-autonomous territory of Denmark.

The president has argued that Greenland is essential for his planned “Golden Dome” missile defense system and has claimed that rival nations are eyeing the territory. Mr. Trump has sought to justify his calls for an American takeover by repeatedly saying that China and Russia have their own designs on Greenland, which holds vast untapped reserves of minerals.

Senator Chris Coons, a Delaware Democrat who traveled to Copenhagen as part of a bipartisan congressional delegation this week, disputed the president’s assessment. “There are no current security threats to Greenland,” Mr. Coons told reporters.

“I hope that the people of the Kingdom of Denmark do not abandon their faith in the American people,” Mr. Coons said. “There is almost no better ally to the United States than Denmark. If we do things that cause Danes to question whether we can be counted on as a NATO ally, why would any other country seek to be our ally or believe in our representations?”

Resistance to the president’s ambitions was visible this week on the streets of Nuuk, Greenland’s capital, where hundreds braved near-freezing rain to march in support of self-governance. Demonstrators carried signs reading “We shape our future” and “Greenland is not for sale.”

Despite the heightened rhetoric, Danish military officials sought to downplay the possibility of armed conflict. Danish Major General Søren Andersen, leader of the Joint Arctic Command, told the Associated Press that Denmark doesn’t expect the U.S. military to attack Greenland or any other NATO ally.

“I will not go into the political part, but I will say that I would never expect a NATO country to attack another NATO country,” General Andersen said aboard a Danish military vessel docked in Nuuk.

However, regarding the unlikely event of American troops using force, General Andersen confirmed that standing orders would require a response. “But you are right that it is Danish law that a Danish soldier, if attacked, has the obligation to fight back,” he said.

The general also noted that in his two and a half years as a commander in Greenland, he hasn’t seen any Chinese or Russian combat vessel, despite claims from the White House.

But Mr. Trump seems undeterred in his determination to take Greenland — one way or another.

“The United States has been trying to do this transaction for over 150 years. Many Presidents have tried, and for good reason, but Denmark has always refused. Now, because of The Golden Dome, and Modern Day Weapons Systems, both Offensive and Defensive, the need to ACQUIRE is especially important,” he wrote on Truth Social.

“Hundreds of Billions of Dollars are currently being spent on Security Programs having to do with ‘The Dome,’ including for the possible protection of Canada, and this very brilliant, but highly complex system can only work at its maximum potential and efficiency, because of angles, metes, and bounds, if this Land is included in it.

“The United States of America is immediately open to negotiation with Denmark and/or any of these Countries that have put so much at risk, despite all that we have done for them, including maximum protection, over so many decades,” he wrote.