Denmark is among the 12 founding members of the NATO military alliance, and Greenland does not have its own independent military, but is part of the alliance through Denmark.

Europe must achieve internal cohesion to create a more balanced strategic interaction with the US, Cui said.

Also on Wednesday, the European Parliament adopted a statement supporting Greenland and Denmark. It said the parliament "unequivocally condemns the statements made by the Trump administration regarding Greenland, which constitute a blatant challenge to international law, to the principles of the United Nations Charter and to the sovereignty and territorial integrity of a NATO ally".

"Such statements are unacceptable and have no place in relations between democratic partners," it said.

Sun Chenghao, head of the US-European Union program at Tsinghua University's Center for International Security and Strategy, said the issue at stake is the predictability of US commitments, which allies value most.

"When the US uses threats, bargaining and coercion rhetoric with allies, it erodes the rule-based boundaries that underpin trans-Atlantic ties," Sun said.

"And Europe is concerned about the uncertainty over how broadly the US may define 'national security'. The Greenland moment deepened Europe's fear that the US selectively adheres to rules and weakens the sense of security that underlies alliance cohesion."

Trump has long said Greenland should be under US control and has become increasingly strident in his demands, despite them putting his country at loggerheads with Denmark, a long-standing ally and fellow member of NATO.

"NATO becomes far more formidable and effective with Greenland in the hands of the United States," Trump wrote on social media. "Anything less than that is unacceptable."

Producing the opposite

However, the threatening rhetoric risks producing the opposite of what he wants, said Charlie Edwards, a senior fellow for strategy and national security at the International Institute for Strategic Studies in London.

"From the moment Trump outlined his intention in 2019 to buy Greenland, his transactional approach to the island has raised profound concerns in Copenhagen and Nuuk regarding the long-term reliability of its most critical partner," he said.

"Albeit, Trump has said the US will do it 'the easy way' or 'the hard way'. Either way, fear of US predation is likely to shift Greenland closer to Denmark in the near term."

Greenlandic Prime Minister Jens-Frederik Nielsen said earlier this week: "One thing must be clear to everyone: Greenland does not want to be owned by the US. Greenland does not want to be governed by the US. Greenland does not want to be part of the US ... If we have to choose between the US and Denmark here and now, we choose Denmark."

xingyi@chinadaily.com.cn