"We have proposed it, the secretary general has taken note of that, and I think we can now -- we hope -- define a framework on how that can be concretised," Poulsen told Danish television.

US President Donald Trump has put the transatlantic alliance to the test with threats to take over Greenland "one way or the other", as European countries close ranks against Washington's designs on the vast Danish autonomous territory.

German and French leaders denounced as "blackmail" weekend threats by Trump to wield new tariffs against countries which oppose his plans for the Arctic island.

Rutte wrote on X that he had discussed "how important the Arctic - including Greenland - is to our collective security" with the Danish minister and Greenland's top diplomat.

"We'll continue to work together as Allies on these important issues," he wrote.

Sweden's defence minister Pal Jonson suggested a NATO mission "could be a way forward" as Trump insists more must be done to ward off the threat of China and Russia to Greenland.

"We are seeing what is the most constructive way that we could contribute to this endeavor of strengthening the alliance footprint in the High North," he said after a meeting of Nordic ministers at NATO headquarters in Brussels.