Denmark's defence ministry has warned that its troops would immediately respond with force to any invasion of Greenland, reaffirming a Cold War-era rule of engagement amid mounting concerns about US intentions toward the Arctic territory. The warning comes as US Secretary of State Marco Rubio prepares to meet Danish officials next week to discuss Washington's interest in Greenland, following repeated statements by US President Donald Trump about acquiring the island. Denmark and Greenland have rejected any unilateral US action, while European allies reaffirm that Greenland's future must be decided by its people and respect international norms.