NATO on Tuesday said "planning is underway" for an Arctic mission, coming weeks after US President Donald Trump frayed the strategic alliance by claiming the US needs to control Greenland to avert unverified security concerns from Russia and China.

Martin O'Donnell, a spokesman for NATO's Supreme Headquarters Allied Powers Europe, told reporters that a "NATO enhanced vigilance activity" will "further strengthen NATO's posture in the Arctic and High North." He did not provide further details as planning has just begun.

It is also unclear where the exercises will take place. Denmark is currently leading an ongoing NATO exercise in Greenland called Operation Arctic Endurance.

Information about the plans was initially reported by Germany's Spiegel newsmagazine, with NATO's commander, US General Alexus G. Grynkewich, having ordered concrete plans to begin for a mission titled "Arctic Sentry."

The magazine reported NATO defense ministers could meet in the coming weeks in Brussels for consultations on the preliminary plans for the operation.

Greenland still wary of Trump

In the run-up to the World Economic Forum annual meeting in Davos last month, Trump alluded to using force to take over Greenland, a large Arctic island with strategic value.

The White House did not walk back Trump's claims, as the president repeated his insistence that the US would "have" Greenland "one way or the other."

With the integrity of the defense alliance in question, Washington's European allies were forced to balance support for Denmark's sovereignty over Greenland with not further antagonizing Trump.

However, after appearing at Davos and meeting with NATO Secretary General Mark Rutte, Trump said he had struck a "framework" deal that would ensure US interests, and appeared to back off on his threats to use force.

Rutte said he had discussed with Trump how NATO allies could work collectively to ensure arctic security. Details of the deal Trump mentioned remain unclear.

On Monday, Greenland's Prime Minister Jens-Frederik Nielsen warned that the US continues seeking "paths to ownership and control over Greenland."

Senior officials from the US, Denmark and Greenland began diplomatic talks last week to "discuss how we can address American concerns about security in the Arctic while respecting the Kingdom's red lines," Denmark's foreign ministry said.

Edited by: Jenipher Camino Gonzalez