U.S. President Donald Trump has doubled down on his threats to take control of Greenland, saying on social media that there is "no going back" and that "Greenland is imperative".

During a news conference at the White House, Trump was asked how far he was willing to go to acquire Greenland and replied, "You'll find out".

Meanwhile, French President Emmanuel Macron warned at a meeting at the World Economic Forum in Switzerland of a "shift towards a world without rules",, while Canadian Prime Minister Mark Carney said the "old order is not coming back".

Trump is due to arrive in Davos on Wednesday, where he has said there are "a lot of meetings scheduled on Greenland".

During the lengthy press briefing, Trump also told reporters that "things are going to work out pretty well" in Greenland.

Asked by the BBC whether the possible break up of the Nato alliance was a price the president was willing to pay for Greenland, he responded, "Nobody has done more for Nato than I have, in every way," and said "Nato is going to be happy and we are going to be happy," adding, "We need it for world security."

But he earlier questioned whether NATO would come to the aid of the US should it be required.

"I know we'll come to (Nato's) rescue, but I just really do question whether or not they'll come to ours," he told reporters.

NATO - the North Atlantic Treaty Organisation - currently has 32 member states, with the US one of the 12 founding countries.

Designed to safeguard freedom and security through a collective defence, one of the core principles of the Nato alliance is outlined in Article 5, which says that an armed attack against one or more members will be considered an attack against all.

Trump has not ruled out using military force to acquire Greenland; when NBC News asked yesterday whether he would use force to seize the territory, the president replied "no comment".

In an interview with BBC Newsnight on Tuesday evening, Greenland's Minister of Industry and Natural Resources, Naaja Nathanielsen, said that Greenlanders were "bewildered" by the president's demands.

"We do not want to be Americans, and we have been quite clear about that," Nathanielsen said.

"What value do you put on our culture and our right to decide what happens with us in the future?"

Tuesday was the first day of the forum in Davos. The President of the European Commission, Ursula von der Leyen, addressed the matter directly in a speech to attendees, emphasising that Europe is "fully committed" when it comes to the security of the Arctic.

However, she said that this could only be achieved together, and called Trump's proposed additional tariffs "a mistake".

The US president has said he will add a 10% tariff to "any and all goods" imported from eight European countries from 1 February if they oppose his proposed takeover of Greenland.

Von der Leyen added that the European Union stands in "full solidarity" with Greenland and the Kingdom of Denmark – adding that their sovereignty is "non-negotiable".

Her words were echoed by Canada's Mark Carney, who said that his country's commitment to Nato's Article 5 – which states an armed attack against one or more members is considered an attack against all – is "unwavering".

"We stand firmly with Greenland and Denmark and fully support their unique right to determine Greenland's future," Carney said.

In Macron's remarks, he said he preferred "respect to bullies" and the "rule of law to brutality".

Earlier on Tuesday, Trump threatened a 200% tariff on French wine and champagne after Macron reportedly declined an invitation to join the Gaza "Board of Peace".

The French president condemned the "endless accumulation of new tariffs" as "fundamentally unacceptable", particularly when used as leverage against territorial sovereignty.

Macron is among those urging the EU to consider retaliatory options against US tariffs, including the anti-coercion instrument, nicknamed a "trade bazooka".

Sources close to the international trade committee have said that the European Parliament is planning to suspend approval of the US trade deal agreed in July, in a move that would mark another escalation in tensions between the US and Europe.