Expert says Trump’s conflict with NATO over Greenland ‘crossed an irreversible line’ and undermines the alliance long-term

European allies and Canada are funneling billions of dollars into aiding Ukraine, and they have pledged to to safeguard their territories.

But despite these efforts, NATO’s credibility as a unified force under U.S. leadership has taken a major hit over the past year as trust within the 32-nation military organization eroded.

The rift has been most glaring over U.S. President Donald Trump’s repeated threats to , a semiautonomous territory of NATO ally Denmark. More recently, Trump’s disparaging remarks about his NATO allies’ troops in Afghanistan .

While the heat on Greenland for now, the infighting has severely undercut the world’s largest security alliance’s ability to deter adversaries, analysts say.

“The episode matters because it crossed a line that cannot be uncrossed,” Sophia Besch from the Carnegie Europe think tank said in a report on the Greenland crisis. “Even without force or sanctions, that breach weakens the alliance in a lasting way.”

The tensions haven’t gone unnoticed in Russia, NATO’s biggest threat.

Any deterrence of Russia relies on ensuring President Vladimir Putin is convinced NATO will retaliate should he expand his war beyond . Right now, that does not seem to be the case.

“It’s a major upheaval for Europe, and we are watching it,” Russian Foreign Minister Sergey Lavrov noted last week.

Filling up the bucket

Criticized by U.S. leaders for decades over low defense spending and relentlessly lashed under Trump, European allies and Canada agreed in July to significantly boost their defense efforts and start investing 5% of their gross domestic product in defense.

The pledge was aimed at taking away Trump’s leverage. The allies would spend the same share of their economic output on core defense as the United States — around 3.5% of GDP — by 2035, plus an additional 1.5% on security-related projects like upgrading bridges, airports, and seaports.

NATO Secretary-General Mark Rutte has hailed those pledges as a sign of NATO’s robust health and military might. He recently said that “fundamentally thanks to Donald J. Trump, NATO is stronger than it ever was.”

Though a big part of his job is to ensure Trump does not pull the U.S. out of NATO (a threat Trump has occasionally made), his has sometimes raised concern. Rutte has pointedly refused to speak about the rift over Greenland.

Article 5 at stake

The North Atlantic Treaty Organization was formed in 1949 to counter the Soviet Union’s security threat during the Cold War, and its deterrence is underpinned by a strong U.S. troop presence in Europe.

The alliance is built on the political pledge that an attack on one ally must prompt a response from all — the collective security guarantee enshrined in of its rule book.

It hinges on the belief that all 32 allies’ territories must remain inviolate. Trump’s designs on Greenland attack that very principle, even though Article 5 does not apply to internal disputes (it can only be triggered unanimously).

“Instead of strengthening our alliances, threats against Greenland and NATO are undermining America’s own interests,” two U.S. senators — Democrat Jeanne Shaheen and Republican Lisa Murkowski — wrote in a New York Times op-ed.

“Suggestions that the United States would seize or coerce allies to sell territory do not project strength. They signal unpredictability, weaken deterrence, and hand our adversaries exactly what they want: proof that democratic alliances are fragile and unreliable,” they said.

Even before Trump escalated his threats to seize control of Greenland, his European allies were never entirely convinced he would defend them if they came under attack.

Trump has said he doesn’t believe the allies would help him either, and he recently drew more anger when he questioned the role of European and Canadian troops who fought and died alongside Americans in Afghanistan. The president later partially reversed his remarks.

In testimony to the Senate Foreign Relations Committee, U.S. Secretary of State Marco Rubio dismissed .

“The stronger our partners are in NATO, the more flexibility the United States will have to secure our interests in different parts of the world,” he said. “That’s not an abandonment of NATO. That is a reality of the 21st century and a changing world.”

A Russia not easily deterred

Despite NATO’s talk of increased spending, Moscow seems undeterred. EU foreign policy chief Kaja Kallas said this week that “it has become painfully clear that Russia will remain a major long-term security threat.”

“We are fending off cyberattacks, sabotage against critical infrastructure, foreign interference and information manipulation, military intimidation, territorial threats, and political meddling,” she said Wednesday.

European officials have reported acts of and mysterious over airports and military bases. Identifying the culprits is difficult, and Russia denies responsibility.

In a year-end address, Rutte warned that Europe is at imminent risk.

“Russia has brought war back to Europe, and we must be prepared for the scale of war our grandparents or great-grandparents endured,” he said.

Meanwhile in Russia, Lavrov said the Greenland dispute heralded a for NATO.

“It was hard to imagine before that such a thing could happen,” Lavrov told reporters, as he contemplated the possibility that “one NATO member is going to attack another NATO member.”

Europe’s “impotent rage” over Trump’s designs on Greenland, and Putin’s presidential envoy declared that “trans-Atlantic unity is over.”

Doubt about US troops

U.S. Defense Secretary Pete Hegseth is due to meet with his NATO counterparts on Feb. 12. A year ago, he startled allies by warning that America’s security priorities and that Europe must look after itself now.

Arctic region security (where Greenland lies) will be high on the agenda. It’s unclear whether Hegseth will announce a new drawdown of U.S. troops in Europe — central to NATO’s deterrence.

Lack of clarity about this has also fueled doubt about the U.S. commitment to its allies. In October, NATO learned that up to 1,500 American troops would be withdrawn from an area bordering Ukraine, .

A report from the European Union Institute for Security Studies warned last week that while U.S. troops are unlikely to vanish overnight, doubts about U.S. commitment to European security mean “the deterrence edifice becomes shakier.”

“Europe is being forced to confront a harsher reality,” wrote authors Veronica Anghel and Giuseppe Spatafora. “Adversaries start believing they can probe, sabotage, and escalate without triggering a unified response.”