Melissa Clarke: A top European intelligence official has warned the Kingdom of Denmark is facing the most serious challenge to its sovereignty since the Second World War, under threat from both the United States and Russia. The country is now embarking on its biggest military build-up in decades, and for the first time conscripting women into its armed forces. Bridget Rolison reports from Denmark.

Bridget Rollason: On a freezing military base in western Denmark, a platoon of young military recruits is learning how to fire in the field. I find it very fun because it requires focus, quickly move between targets and being able to just hit. It’s pretty cool. It’s a cool skill. As Denmark finds itself under threat on two fronts, it’s now compulsory for all 18-year-old Danish women to register for the military for the first time. If the armed forces don’t get enough volunteers, they could be called up to serve. The move comes as US President Donald Trump’s recent threats to seize Greenland, an autonomous region of Denmark, shocked the nation.

Jacob Carlsbo: By turning on an ally like Denmark, there’s a sense of betrayal and a sense of being stabbed in the back.

Bridget Rollason: Former chief analyst of the Danish Defence Intelligence Service, Jacob Carlsbo, says it’s been a turning point.

Jacob Carlsbo: It’s the most direct challenge to Danish territorial integrity and sovereignty since we were attacked by Nazi Germany in 1939. The

Bridget Rollason: unexpected threat from within the NATO alliance comes as Denmark faces rising Russian aggression after a wave of drone incursions widely blamed on Moscow. As a result, Denmark is embarking on its biggest military build-up in decades, investing billions of dollars in fighter jets, drones and ships. Head of Danish conscription, Colonel Kenneth Strem, says the country is also tripling the length of its military service to 11 months in preparation.

Jacob Carlsbo: I think that everyone would like to have no war, but that might not be the reality. Based on the Danish Defence Intelligence Service, Russia could pose a threat towards the Baltic region within two years.

Bridget Rollason: Many in Denmark believe the falling out with the US over Greenland has left it more exposed to Russia. I’m

Jacob Carlsbo: sure Putin would be delighted with what he’s seeing. It’s what the Russians and what the Kremlin has been striving for for many years, because NATO has always been their main enemy and it’s playing right into his whole argument.

Bridget Rollason: Jacob Carlsbo says Europe should forge a military alliance that doesn’t rely on the US. He warns the feud with America will likely flare up again, despite Donald Trump dialing back his most inflammatory rhetoric to take over Greenland.

Jacob Carlsbo: We don’t know, so we have to be prepared.

Melissa Clarke: Jacob Carlsbo, former chief analyst of the Danish Defence Intelligence Service, ending that report from Bridget Rolison in Denmark.