Danish troops will immediately respond to any invasion of Greenland with force, the country’s defence ministry warned as the US continues to weigh up military intervention to annex the territory.

Axar.az, citing The Independent, reports that the ministry told Danish outlet Berlingske that soldiers would be required to counter any foreign invasion without awaiting orders under the military’s rules of engagement.

It said a Cold War-era rule requiring troops to “immediately take up the fight” if attacked remains in force as European leaders contend with how to respond to Donald Trump’s repeated threats to seize the island.

The 1952 rule states that in the event of an invasion, forces should respond “without waiting for or seeking orders, even if the commanders in question are not aware of the declaration of war or state of war.”

Denmark’s European allies have rallied behind the country and said they are working on a unified response after the White House said that Trump is still considering the possibility of taking Greenland by force.