"Arctic Sentry underscores the alliance's commitment to safeguard its members and maintain stability in one of the world's most strategically significant and environmentally challenging areas," said US General Alexus Grynkewich, NATO's Supreme Allied Commander Europe.

NATO said the "multi-domain activity" would initially pull together work already being carried out by alliance members in the region such as upcoming exercises by Norway and Denmark.

Denmark's defence minister said his country would contribute "substantially" to the newly-launched NATO mission, and Germany said it would send an initial four eurofighter jets to take part.

Finland, which shares a 1,340-kilometre (833-mile) border with Russia, hailed the NATO initiative as strengthening security in the Arctic.

But it remained unclear whether many additional military capabilities would be deployed to the region under the new mission.

"What is really new about it is that for the first time now, we will bring everything we do in the Arctic together under one command," NATO chief Mark Rutte said ahead of a meeting of alliance defence ministers.

"We will also be able to assess what gaps there are, which we have to fill and of course we will fill them."

Trump's threats against Greenland last month -- which he based on an alleged threat by Russia and China in the Arctic -- plunged the transatlantic alliance into its deepest crisis in years.

- Trump's 'framework' -

The unpredictable US leader backed off his vow to take control of Denmark's autonomous Arctic territory after saying he had struck a "framework" deal with Rutte to ensure greater American influence.

"The two leaders agreed that NATO should collectively take more responsibility for the defence of the region considering Russia's military activity and China's growing interest there," NATO said in a statement.

Denmark and Greenland have meanwhile kicked off talks with the US over the territory and are expected to renegotiate a 1951 treaty governing American troop deployments on the island.

Danish Prime Minister Mette Frederiksen has said that NATO countries back having a "permanent presence" in the Arctic, including around Greenland, as part of efforts to step up security.

The launch of Arctic Sentry comes after NATO last year deployed emergency missions in the Baltic Sea and along its eastern flank to try to shore up protection against Moscow.