Denmark has confirmed that its soldiers are legally required to open fire immediately if the country or its territories are invaded, even without waiting for orders from senior commanders. This decades-old military rule has come into focus as US President Donald Trump continues to say that the United States needs to take control of Greenland, raising concerns in Europe.

The rule dates back to 1952 and was created during the Cold War. According to the order, Danish forces must respond instantly to any foreign invasion. Soldiers are instructed to begin defending the country right away, even if there has been no official declaration of war or if commanders are not yet aware of the situation. The Danish Defence Ministry confirmed on January 7 that this rule is still active.

The issue gained attention after Trump repeatedly said that Greenland is important for US national security. Greenland is a self-governing territory under Denmark and lies in a strategically important Arctic region. Trump has argued that the US needs Greenland to counter growing influence from Russia and China. His comments included suggestions that the US could try to acquire the island through purchase or, if necessary, by force.

The White House confirmed that the idea of buying Greenland is being discussed seriously. Press Secretary Karoline Leavitt said Trump prefers diplomacy but added that “all options are on the table.” This statement caused alarm among European leaders, who see Greenland as an integral part of Danish territory.

In response, leaders from Denmark, the UK, France, Germany, Italy, Poland and Spain issued a joint statement saying they would defend Greenland’s territorial integrity. They stressed that Greenland is not for sale and must remain under Danish control.

Trump reacted strongly to the statement, criticising NATO allies and accusing them of not contributing enough to defence spending. He claimed the US had been paying for Europe’s security and repeated his earlier statements that he pushed NATO members to increase defence budgets.

While Denmark has not issued new military threats, its confirmation of the 1952 rule shows it is prepared to defend its territory if required. The situation has increased diplomatic tensions but there is no immediate sign of military conflict.