Donald Trump takes aim at Greenland's defence system as 'two dog sleds'

Donald Trump has ramped up his push for the United States to acquire Greenland, taking aim at its defence system as being "two dog sleds".

Speaking on board Air Force One as he returned to Washington on Sunday night (Monday AEST), the US president insisted that "one way or another, we are going to have Greenland".

"If we don't take Greenland, Russia or China will, and I'm not letting that happen," he told reporters.

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"They don't go there, it's very far away from Greenland. And Greenland, basically, their defence is two dog sleds, do you know that?

"You know what their defence is? Two dog sleds. In the meantime, you have Russian destroyers and submarines and China destroyers and submarines all over the place.

"We're not going to let that happen."

The president did not provide any evidence that Russian or Chinese vessels are present in the oceans surrounding Greenland, or even go there at all.

His latest comments appear to double down on his call for a full takeover of Greenland, which he reiterated during an interview with The New York Times published last week.

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Trump said full American ownership of the critical mineral-rich island – which is the territory of Denmark, one of the United States' allies in NATO – was necessary "because that's what I feel is psychologically needed for success".

"I think that ownership gives you a thing that you can't do, whether you're talking about a lease or a treaty," he said.

"Ownership gives you things and elements that you can't get from just signing a document, that you can have a base."

In that interview, he reiterated that it was "psychologically important" for him, not necessarily the United States.

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"Now, maybe another president would feel differently, but so far I've been right about everything."

The incendiary nature of the president's messaging has set off fresh alarm bells in Europe about the future of NATO.

In an official statement, Greenland's government vowed to "increase its efforts to ensure that the defence of Greenland takes place under the auspices of NATO".

"All NATO member states, including the United States, have a common interest in the defence of Greenland, and the government coalition in Greenland will therefore work with Denmark to ensure that the dialogue on and development of the defence in Greenland takes place within the framework of NATO co-operation," the statement said.

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