The European Union can help provide security for Greenland, should Denmark request it, the European Commissioner for Defence and Space said on Monday, warning that a US military takeover of Greenland would be the end of NATO.

Trump has said the United States must own Greenland, an autonomous part of the Kingdom of Denmark, to prevent Russia or China from occupying the strategically located and minerals-rich Arctic territory. He says a US military presence there is not enough.

Denmark and the US, both NATO members, are scheduled to meet this week to discuss Greenland. Greenland and Denmark have said that Greenland is not for sale, but Trump has not ruled out taking it by force.

“I agree with the Danish prime minister that it will be the end of NATO, but also among people it will also be very, very negative,” Commissioner Andrius Kubilius at a security conference in Sweden.

He said it would have a “very deep negative impact among the people and on our transatlantic relations”.

Trump said, “I’m the one who SAVED NATO!!!” on Truth Social on Monday, without giving further details or context.

Kubilius said he did not think a US military invasion was coming but that the European Union Treaty article 42.7 obliged member states to come to Denmark’s assistance if it was faced with military aggression.

“It will depend very much on Denmark, how they will react, what will be their position, but definitely there is such an obligation of member states to come for mutual assistance if another member state is facing military aggression,” he said.

Kubilius questioned the rationale of occupying Greenland by force and warned that it would have impacts on all aspects of the relations between Europe and the United States.

“Who will recognise that occupation and what impacts on all the relationship in between the United States and Europe, including, for example, trade, where Americans can face quite painful negative consequences,” he said.

Kubilius said the EU could provide more security for Greenland, if Denmark requested it, including troops and military infrastructure such as warships and anti-drone capabilities.

“That’s for military people to say what Greenland or the Arctic defence needs. Everything is possible,” he said.

Kubilius also said Europe needed to build up its military capabilities, regardless of whether it could rely on US help, but that any US withdrawal from NATO would be very tough.

“It will be a very big challenge to be ready to defend Europe, being independent, being without the United States,” he said.

“The question would be how we can use in that case NATO structures, how they can be, you know, become a basis for the European pillar of NATO. But NATO such as it is now, definitely will not exist anymore.”

Trump said last week the US would always support NATO and that Russia and China only feared the alliance as long as the United States was a member.

Many NATO countries have substantially increased military spending in recent years, following Russia’s 2022 invasion of Ukraine and demands by Trump for European allies to invest more in their own defence.