European Commission President Ursula von der Leyen has warned against Donald Trump's threat of tariffs of up to 25% for eight European countries, which the US president said he will impose until a deal is reached for the US to purchase Greenland.
Mr Trump said those tariffs will then increase to 25% from 1 June.
In response, Ms von der Leyen said: "Tariffs would undermine transatlantic relations and risk a dangerous downward spiral," she wrote in a post on social media.
"Europe will remain united, coordinated, and committed to upholding its sovereignty."
Ambassadors from the European Union's 27 countries will convene tomorrow for an emergency meeting following Mr Trump's latest threat.
Cyprus, which holds the six-month rotating EU presidency, said it had called the meeting for tomorrow, with EU diplomats saying that it is due to start at 5pm.
In a joint statement, Ms von der Leyen and European Council president Antonio Costa said: "Territorial integrity and sovereignty are fundamental principles of international law."
"They are essential for Europe and for the international community as a whole.
"We have consistently underlined our shared transatlantic interest in peace and security in the Arctic, including through NATO.
"The pre-coordinated Danish exercise, conducted with allies, responds to the need to strengthen Arctic security and poses no threat to anyone," they said.
"The EU stands in full solidarity with Denmark and the people of Greenland. Dialogue remains essential, and we are committed to building on the process begun already last week between the Kingdom of Denmark and the US.
"Tariffs would undermine transatlantic relations and risk a dangerous downward spiral. Europe will remain united, coordinated, and committed to upholding its sovereignty," they added.
Tariffs imposed by the US on European allies undermine prosperity on both sides of the Atlantic and play into the hands of China and Russia, the EU's foreign policy chief Kaja Kallas has said.
"China and Russia must be having a field day. They are the ones who benefit from divisions among allies," Mr Kallas said in a post on X.
"Tariffs risk making Europe and the United States poorer and undermine our shared prosperity. If Greenland's security is at risk, we can address this inside NATO," he added.
In a statement, UK Prime Minister Keir Starmer said: "Our position on Greenland is very clear - it is part of the Kingdom of Denmark and its future is a matter for the Greenlanders and the Danes.
"We have also made clear that Arctic Security matters for the whole of NATO and allies should all do more together to address the threat from Russia across different parts of the Arctic," he said.
"Applying tariffs on allies for pursuing the collective security of NATO allies is completely wrong. We will of course be pursuing this directly with the US administration."
Reform leader Nigel Farage said Mr Trump's Greenland tariffs would hurt the UK.
"We don’t always agree with the US government and in this case we certainly don’t. These tariffs will hurt us," he said.
"If Greenland is vulnerable to malign influences, then have another look at Diego Garcia."
Macron labels threat as 'unacceptable'
France's President Emmanuel Macron said the threat over Greenland was unacceptable and that if they were confirmed Europe would respond in a coordinated manner.
"No intimidation nor threat will influence us, neither in Ukraine, nor in Greenland, nor anywhere else in the world when we are confronted with such situations," Mr Macron said on X.
"Tariff threats are unacceptable and have no place in this context. Europeans will respond to them in a united and coordinated manner if they were to be confirmed."
Swedish Prime Minister Ulf Kristersson rejected Mr Trump's threat to European nations of swingeing tariffs if they did not let him acquire Greenland. "We won't let ourselves be intimidated," he said.
"Only Denmark and Greenland decide questions that concern them. I will always defend my country and our allied neighbours," he added, stressing that this was "a European question".
"Sweden is currently having intensive discussions with other EU countries, Norway and the United Kingdom to find a joint response," he added.
Finland's prime minister Petteri Orpo said tariffs would be in "no-one’s interest" and would harm the US and Europe.
Issues among allies are resolved through discussion, says Finland
Writing on social media, he said: "Finland’s position is that issues among allies are resolved through discussion and shared rules, not by creating pressure. The United States has raised concerns related to the Arctic region. Arctic security is an important issue for Finland.
"Finland wants to strengthen Arctic security together with all allies, while respecting the territorial integrity of Denmark and Greenland.
"I understand the concerns of Finns. Tariffs would be harmful to both Europe and the United States. They are in no-one’s interest.
"We are working closely with our European partners and allies. We are ensuring the security of Finland and Finns."
Norway's Prime Minister Jonas Gahr Store wrote on social media: "Threats have no place among allies. Norway’s position is firm: Greenland is part of the Kingdom of Denmark.
"Norway fully supports the sovereignty of the Kingdom of Denmark. There is broad agreement in NATO on the need to strengthen security in the Arctic, including in Greenland."
Labour TD George Lawlor said the EU "cannot give in to this latest round of bullying, and attempts at extortion".
"Ireland and the EU must prepare for the risk of a chronic breakdown of relations with the United States and ensure measures are in place to support businesses and workers.
"The Irish government must now clarify what contingency plans and measures are in place in the event of a hard break with the US," said Mr Lawlor.
Additional reporting by PA
