The unthinkable prospect of Nato turning its guns on itself has edged closer to reality, after senior figures warned that any US military move to seize Greenland would fatally undermine the alliance.
Lord Peter Ricketts, the former UK ambassador to Nato, has issued a stark warning that the transatlantic alliance would no longer be viable if the United States attempted to annex Greenland by force, a scenario now being openly discussed in Washington.
His comments come amid growing alarm in Europe after the White House confirmed that President Donald Trump is actively considering “a range of options” to acquire the strategically vital Arctic territory, including the possible use of military power.
White House press secretary Karoline Leavitt said the president views Greenland as a “national security priority”, citing the need to counter rival powers in the Arctic. She added that military action was “always an option” available to the commander-in-chief.
Greenland is a semi-autonomous territory governed by Denmark, a fellow Nato member, and any armed attack would trigger Nato’s Article 5 collective defence clause, obliging allies to respond.
Speaking to reports, Lord Ricketts said such a move would strike at the very heart of Nato.
“If one ally uses military force to annex the territory of another ally, that destroys the fundamental trust Nato is built on,” he said. “At that point, Nato would no longer be an effective alliance.”
He added that the treaty itself would struggle to survive such an unprecedented breach.
From bluster to real risk
Lord Ricketts said he had initially dismissed Trump’s Greenland ambitions as rhetorical brinkmanship, aimed at extracting concessions from Denmark. But he warned the tone has changed following the US military operation in Venezuela.
“Trump thrives on unpredictability,” he said. “After the assault on Maduro, he feels emboldened. I don’t think we can rule anything out anymore.”
European leaders have moved quickly to close ranks. Prime Minister Sir Keir Starmer has publicly backed Denmark and Greenland, and spoke directly with Trump on Wednesday evening to outline the UK’s position. Downing Street declined to give details of the conversation.
Greenland, the world’s largest island, is strategically significant due to its Arctic location, rare earth minerals and proximity to emerging polar shipping routes. While largely self-governing, defence and foreign policy remain the responsibility of Copenhagen.
Nato diplomacy under strain
Attention is now turning to Nato Secretary General Mark Rutte and whether he can defuse the crisis behind closed doors. Lord Ricketts suggested Mr Rutte should urgently engage Trump directly.
“This is the moment to quietly explain the damage that would be done by any hostile move,” he said. “Trump does listen to people he respects.”
Mr Rutte is believed to have a warm personal relationship with Trump, previously describing him as “a good friend” during last year’s Nato summit, comments the former US president appeared to enjoy.
No UK war with the US
Despite the gravity of the situation, Lord Ricketts ruled out any prospect of British forces clashing with American troops.
“There is simply no conceivable scenario where British forces go to war with the United States over Greenland,” he said.
Denmark currently defends Greenland through its Joint Arctic Command, based in Nuuk, with a small but capable mix of patrol vessels, aircraft and surveillance assets.
For now, diplomacy remains the only barrier between Nato unity and a crisis that could redefine the alliance, or end it altogether.
