Washington DC - President Donald Trump has "actively discussed" the purchase of Greenland with his team, the White House said Wednesday, saying he preferred diplomacy but would not rule out military action.

"That's something that's currently being actively discussed by the president and his national security team," Press Secretary Karoline Leavitt said when asked about a possible US offer to buy the territory from Denmark.

"His team is currently talking about what a potential purchase would look like."

Leavitt reiterated that Trump believes acquiring Greenland would be in the interest of US national security.

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"He views it in the best interest of the United States to deter Russian and Chinese aggression in the Arctic region. And so that's why his team is currently talking about what a potential purchase would look like."

Asked why Trump would not rule out military action against a fellow NATO member, Leavitt replied: "That's not something this president does. All options are always on the table for President Trump.

"But I will just say, the president's first option, always, has been diplomacy."

Secretary of State Marco Rubio said separately Wednesday that he planned to meet next week with Denmark, which requested talks after Trump's threats to Greenland.

"I'll be meeting with them next week," Rubio told reporters.