French President Emmanuel Macron said as he arrived in Greenland that his visit aimed to show the solidarity of France and the European Union over the Arctic island's "sovereignty" and "territorial integrity".
US President Donald Trump has said he wants the United States to take over the minerals-rich and strategically-located Arctic island for reasons of national and international security, and has not ruled out the use of force to do so.
Greenland is a self-governing part of the Kingdom of Denmark with the right to declare independence.
Both the Greenland and Danish governments say it is not for sale and only Greenlanders can determine their future.
US Vice President JD Vance visited a US military base there in March.
President Macron, the first foreign leader to visit Greenland since Mr Trump's explicit threats to "get" the island, was invited by the prime ministers of Greenland and Denmark.
He has said his visit is meant to prevent any "preying" on the territory.
"France has stood by us since the first statements about taking our land emerged.
"This support is both necessary and gratifying," Greenland's Prime Minister Jens-Frederik Nielsen wrote on Facebook days ahead of Mr Macron's visit.
Asked if President Macron would deliver an explicit message to the United States during his visit, an adviser to Mr Macron told reporters: "The trip is a signal in itself," without mentioning Donald Trump.
Earlier, speaking on RTL radio, French Foreign Minister Jean-Noel Barrot said: "Greenland is a European territory and it is normal that Europe and notably France show their interest."
According to an IFOP poll for NYC.eu published yesterday, 77% of the French and 56% of Americans disapprove of an annexation of Greenland by the US and 43% of the French would approve using French military power to prevent a US invasion.
Mr Macron is visiting the capital Nuuk, as well as a hydropower station funded by the EU and a glacier, and discuss Arctic security and climate change with his hosts.
Though Denmark is an EU member, Greenland is outside the EU.
The French adviser said the visit would be an opportunity to discuss how to give Greenland's association partnership with the EU a "new dimension".
Danish Prime Minister Mette Frederiksen made several visits to Paris after Mr Trump's threats to seek French and European backing, and has placed orders for French-made surface-to-air missiles, in a shift of focus for Copenhagen.
Enlisting the EU's only nuclear power is a way for Denmark, long one of the US’s most loyal allies in Europe, to project a form of hard power towards a suddenly more aggressive United States, said Florian Vidal of the Paris-based IFRI think tank.
"The Trump administration's more aggressive posture is a shock that makes the French vision of Europe, one that is more autonomous, appear more reasonable for Denmark," he said.
"From a Nordic point of view, France is a military power that counts," he added.
