Denmark is increasing military spending in the North Atlantic amid President Donald Trump’s bid to have Greenland sold or ceded to the United States.

BRUSSELS (Reuters) -NATO Secretary-General Mark Rutte and Danish Prime Minister Mette Frederiksen agreed at a meeting on Tuesday that allies need to focus on strengthening defences in the Arctic, a source familiar with the talks told Reuters.

Denmark's Prime Minister Mette Frederiksen said on Tuesday following a meeting with French President Emmanuel Macron that political leaders in Europe and beyond have given full backing to maintain respects for international borders.

Denmark's prime minister plans stops in Berlin, Paris and Brussels on tour of European capitals as Copenhagen moves to strengthen its presence in Greenland.

Frederiksen will meet German Chancellor Olaf Scholz in Berlin, French President Emmanuel Macron in Paris and NATO Secretary-General Mark Rutte in Brussels, during a whirlwind day of international diplomacy as Trump threatens to upend the polar security architecture.

Denmark is in “crisis mode” after Donald Trump made a direct play for Greenland in a “horrendous” phone call with the country’s prime minister.

Trump has shown interest in making Greenland part of the US and has not dismissed the use of military or economic power.

German Chancellor Olaf Scholz has warned of the threat posed by hybrid warfare from Moscow after an underwater Baltic Sea cable was severed. Scholz was speaking as he met Danish Prime Minister Mette Frederiksen.

The poll, which surveyed 497 Greenlandic citizens, revealed that 45 percent of respondents said they view Trump's interest in their territory as a threat, while only 8 percent would accept a U.S. passport if given the choice between American and Danish citizenship.

Trump’s bid for the Arctic territory was laughed off as a joke. Now, it’s gaining traction and provoking jitters in Europe.

The Danish PM's tour of three capitals betrayed the nervousness felt in Denmark over Trump's repeated comments.