How NATO works at a time when Trump is threatening to seize Greenland

BRUSSELS (AP) — President Donald Trump’s repeated threats to seize control of Greenland are straining relations with U.S. allies in NATO and have sparked a warning that doing so by force could spell the end of the world’s biggest security alliance.

Tensions have routinely spiked among some of NATO’s members over the decades, notably between neighbors Greece and Turkey. But it would set a dangerous precedent should its most powerful country, the United States, annex the territory of another ally.

“One way or the other, we’re going to have Greenland,” Trump reaffirmed on Sunday. The White House has not ruled out the use of military force. Trump said he wants to prevent Russia or China from taking over and that making a deal would be “easier.”

Greenland is a semi-autonomous island that is part of the Danish realm. Danish Prime Minister Mette Frederiksen has warned that “if the United States chooses to attack another NATO country militarily, then everything stops … including our NATO.”

The North Atlantic Treaty Organization was formed by 12 nations in 1949 to counter the security threat posed by the Soviet Union during the Cold War. NATO’s deterrence works through a strong American troop presence in Europe, with U.S. nuclear weapons stationed there.

Its ranks have grown since the founding Washington Treaty was signed to 32 countries after Sweden joined in 2024, worried by an increasingly aggressive Russia. Indeed, NATO officially considers its biggest threats to be Russia and international terrorism.

NATO’s doors are open to any European country that wants to join and can meet the requirements and obligations. Importantly, NATO takes its decisions by consensus, so every member has a veto. The Trump administration has vetoed Ukraine’s application.

NATO is built on the principle that an attack on any one of its ranks must be considered an attack on them all — the collective security guarantee enshrined in Article 5 of the treaty. The organization’s credibility depends on adversaries believing that all 32 allies will make good on that pledge.

It’s a political commitment and not a legal obligation that can be enforced by any court. The only time it has ever been activated was in 2001, to support the United States in the wake of the 9/11 attacks on New York and Washington.

Trump said last year that he is committed to the Article 5 pledge, but he has also fueled doubt about whether he would defend allies who don’t spend enough on defense. However, his repeated threats against Greenland take things to a new level.

Article 5 would be moot in any U.S.-Denmark fight as there would be no unanimity to activate it. Besides diplomacy, NATO has no obvious way of dealing with open conflict among its members. Senior U.S. and Danish officials were due to hold talks on Wednesday.

Should things get worse, Denmark could trigger Article 4 of the treaty for official consultations if it feels that its sovereignty or territorial integrity is threatened. Article 4 talks do not automatically lead to any action.

A U.S. attack is almost certain to divide NATO. This happened when the United States led an attack on Iraq in 2003, with Britain and Spain backing while France and Germany led a group of others vehemently opposed.

It’s unclear which allies would side with Trump over Greenland.

The United States is NATO’s most powerful member. In real terms, it spends much more on defense than any other ally and far outweighs its partners in terms of military muscle. Washington has traditionally driven the agenda but has stepped back under Trump.

NATO is weaker without U.S. leadership, troops, equipment or other military assets. It’s almost inconceivable that any ally would go to war with it, let alone hope to win.

Day-to-day work at the alliance’s Brussels headquarters is led by former Dutch Prime Minister Mark Rutte.

As NATO’s top civilian official, he chairs meetings of ambassadors in the North Atlantic Council most weeks. He chairs other “NACs” at ministerial level and summits of heads of state and government. Rutte runs NATO HQ, encourages consensus and speaks on behalf of all 32 members.

One of his main tasks is to ensure that the United States remains committed to NATO. As a result, he does not criticize Trump, and on Monday he sidestepped questions about Greenland and any NATO tensions over the island.

“All allies agree on the importance of the Arctic and Arctic security because we know that with sea lanes opening up there is a risk that the Russians and the Chinese will be more active,” Rutte told reporters.

Asked whether NATO was in crisis over Greenland, Rutte said: “No, not at all."

NATO’s military headquarters is based nearby in Mons, Belgium. It is always run by a top American officer. The current supreme allied commander, or SACEUR, is Air Force Lt. Gen. Alexus Grynkewich. Trump is his commander in chief.

Denmark's Prime Minister Mette Frederiksen departs after a meeting of the 'Coalition of the Willing' on Ukraine at the Elysee Palace in Paris, France, Tuesday, Jan. 6, 2026. (AP Photo/Michel Euler)

President Donald Trump waves after arriving on Air Force One from Florida, Sunday, Jan. 11, 2026, at Joint Base Andrews, Md. (AP Photo/Julia Demaree Nikhinson)

FILE - Danish military forces participate in an exercise with hundreds of troops from several European NATO members in the Arctic Ocean in Nuuk, Greenland, Sept. 15, 2025. (AP Photo/Ebrahim Noroozi, File)

NATO Secretary General Mark Rutte, center, is welcomed by Croatian Prime Minister Andrej Plenkovic, in Zagreb, Croatia, Monday, Jan. 12, 2026. (AP Photo/Darko Bandic)

A teacher who survived the 2022 shooting inside a Robb Elementary school classroom in Uvalde, Texas, told a jury Monday the attack began with a “black shadow” with a gun walking inside and that he prayed for the attack to be over after being shot along with his students.

Arnulfo Reyes' testimony came on the fifth day of the trial for Adrian Gonzales, a former Uvalde schools police officer who was among the first law enforcement responders to the scene. Gonzales has pleaded not guilty to 29 counts of child abandonment or endangerment as prosecutors allege he did nothing to stop the gunman in the first moments of the attack.

The gunman killed 19 students and two teachers. Reyes was shot on the arm and back and said he was taunted by 18-year-old gunman Salvador Ramos.

“I looked at my door and that’s when I saw him ... a black shadow. The black shadow was holding a gun. I just saw the fire come out of the gun," Reyes testified. “He shot at me and hit me in my arm. That’s when I fell to the ground.”

“When I fell, he came around and he shot the kids,” he said.

Reyes said Ramos turned back around and shot him in the back. He prayed “and I gave myself to the Lord ... and waited for everything to be over.”

Reyes said the gunman at one point walked into the adjoining classroom, where he said he heard a student say, “Officer, we’re in here,” before he heard more shooting.

Reyes said Ramos also taunted him while he tried to pretend he was dead.

Reyes was a teacher in Room 111. None of the children in his classroom survived.

Just before Reyes testified, the court watched the surveillance video of Ramos entering the school and start shooting. The judge had warned the courtroom the images and sounds would be graphic.

Gonzales showed no emotion on his face as emergency calls to police and a woman can be heard screaming “get in your room!” He appeared to flinch when the first loud shots rang out in the hallway. He also covered his mouth with his left hand.

Gonzales was among the first of more than 370 federal, state and local officers to arrive at the school. It would take more than an hour for a tactical team to go into a classroom and kill the gunman.

The trial in Corpus Christi, Texas, is tightly focused on Gonzales’ actions. Prosecutors allege he abandoned his active shooter training and did not try to engage or distract the gunman while he was still outside the school. They said Gonzales failed again minutes later when a group of officers went inside the school only to retreat when they came under heavy gunfire.

While much of the trial has been focused on events outside the school when the attack started, prosecutors are using the carnage inside the classroom as the ultimate result of what they said was Gonzales’ failure to stop the gunman when he had a chance.

At one point, prosecutors showed the school portraits of each of the schoolchildren and asked Reyes to read their names and say whether they died or survived.

Reyes was not asked about Gonzales during questioning by prosecutors, and mentioned only encountering a Border Patrol officer when the shooting stopped.

At the start of their cross-examination, defense attorneys noted the doors to the outside of the school, as well as Reyes' classroom, were unlocked in violation of school policy. Reyes said he'd believed his classroom door was locked.

Reyes' testimony will continue Tuesday.

The opening days of the trial included dramatic replays of the initial emergency calls, testimony from teachers who huddled with terrified students, and the mother of one of the victims recounting how her daughter had asked to leave school early that day.

Jurors have also seen graphic photos from inside the school and classrooms. Prosecutors noted how students made 911 calls from inside the classroom with the gunman.

The trial is a rare case in which a police officer could be convicted of allegedly failing to act to stop a crime and protect lives.

Gonzales and former Uvalde schools Police Chief Pete Arredondo are the only two responding officers that day to face charges. Arredondo’s trial has not yet been set.

FILE - Crosses with the names of shooting victims are placed outside Robb Elementary School in Uvalde, Texas, May 26, 2022. (AP Photo/Jae C. Hong, File)