Something in Europe has snapped. Donald Trump doubled down again on Monday, in his insistence that the US needs Greenland for national security reasons.

Is he prepared to use force to seize it, journalists asked him? No comment, said the president, sending chills down the spine of Greenland's anxious inhabitants.

Greenland is a semi-autonomous territory of Denmark - a member of the EU and of Nato. President Trump is now leaning heavily on Denmark's allies in both those organisations to abandon Copenhagen and let the US take control of Greenland, or face punitive taxes on all their exports to the United States.

It's a horror scenario for European economies, which are already in the doldrums. Especially those reliant on exporting to the US, like Germany's car industry and Italy's luxury goods market.

It's too early to read the last rites on transatlantic relations altogether but the EU, at least, is hoping to approach the US president in Switzerland this Wednesday at the Global Economic Forum speaking softly, while carrying a big stick to paraphrase a former US president.

European leaders are telling President Trump they'll support him in prioritising Arctic security, so there's no need for him to go it alone over Greenland.

At the same time, EU diplomats have let it be known they're considering imposing €93 billion (£80 billion) worth of tariffs on US goods or even restricting the access of American businesses, possibly including banks and high tech companies - to the bloc's massive single market, if Trump goes ahead with his Greenland tariffs as they've become known.

On Monday Germany's finance minister said, we will not allow ourselves to be blackmailed after an emergency meeting with his French counterpart.

The Trump threats landed like a slap in the face of European governments, who (separately, in the case of the EU and the UK) had only just settled tariff deals with the US president last year.

A line has been crossed... You'll understand that today I'm not saying exactly what will happen. But one thing must be clear: Europe must be prepared.

Claims add to a growing sense of unease in Europe, particularly about American reliability in security matters. The EU and its members want to show that they can be taken seriously in dealing with the challenges – economic and geopolitical – posed by the U.S. and how they impact their sovereignty.

As global dynamics shift, President Trump’s renewed focus on Greenland reveals the complexity of international relations and underscores Europe's need for unity and a firm stance in the face of perceived threats to its autonomy.