The US president has said risking war against Denmark is necessary to prevent Russia or China taking the world's biggest island.

In an apparent escalation of threats against NATO ally Denmark, US President Donald Trump on Friday said the US must take Greenland to prevent Russia or China from taking it.

What did Trump say about Greenland?

"We are going to ⁠do something on Greenland whether they like it or not," the president told reporters at the White House while meeting with oil company executives.

"Because if we don't do it, Russia or China will take over Greenland, and we're ⁠not going to have Russia or China as a neighbor," he added.

Trump has previously said he would not rule out using military force to take the largely ice-covered island that has a population of 57,000.

"I would like to make a deal, you know, the easy way, but if we don't do it the easy way, we're going to do it the hard way," he said on Friday.

When it was pointed out that the US leases bases on the Danish-ruled island, with the option of deploying as many soldiers as it wants, Trump responded: "You defend ownership. You don't defend leases. And we'll have to defend Greenland. If we don't do it, China or Russia will."

How has Europe responded to Trump's threats over Greenland?

Trump has repeatedly said he wants control over Greenland, but the rhetoric has escalated since the US carried out operations to "capture" Venezuelan President Nicolas Maduro.

Aside from military intervention, the Trump administration has suggested offering payment to Greenlanders to convince them to secede from Denmark and join the US.

Denmark has said any military action would mean the end of the NATO alliance.

Other European leaders have also reacted with disdain to Trump's comments, although the response has remained reserved.

Germany, France, Italy, Poland, Spain, the UK and Denmark issued a joint statement on Tuesday saying only Greenland and Denmark can decide on their future.