Prince Harry will join one of Britain’s biggest war exercises against Russia in 20 years, as a warning to Vladimir Putin over his continued aggression.
The royal secretly agreed to be with Marines in Norway, who are training to repel an invasion.
A source said: “Harry will be totally immersed in the exercise.”
As tensions between the West and Russia grow to almost Cold War levels, the Duke will be present in the country as the marines practice drills in a show of strength against potential military strikes by Moscow
And the war veteran is said to be relishing joining the Royal Marines on the front line of an arctic exercise aimed at warning Vladimir Putin that Britain and her allies have the power to hit back.
Harry has secretly agreed to join more than 1,000 elite commandos practising a counter-attack against a Russian invasion of Norway, which lies on Europe’s northern flank against Russia and is vulnerable to invasion.
Sources say the 34-year-old former Army Captain, who is also head of the Royal Marines, will spend time visiting the marines while the multi-million pound war games are taking place over 12 weeks, signed off by Defence Secretary Gavin Williamson.
A senior military source said: “Prince Harry will be totally immersed in the exercise, and he will be privy to top-secret battle plans.
“It will be high-tempo, extremely realistic and his involvement is good news for the Marines, who will see his involvement as a very positive message of encouragement to the Corps.
“They are the main force who will protect Europe’s northern flank in the event of a conflict, the tip of the spear, and it is important Harry is among the troops.”
The Duke of Sussex, who fought in Afghanistan as a Cavalry officer and Apache helicopter pilot, has told his closest confidants of his excitement at being back in the military fold.
A palace source said: “The duke is relishing his role with the Royal Marines and taking it extremely seriously.
“His grandfather Prince Philip carried out his duty with the Marines with such distinction, which Harry particularly admired.
“Throughout his military career, Harry always had the greatest of respect and admiration for the Marines and he has always been fascinated by their valour and courage.”
The Norway manoeuvres will be the biggest Arctic military exercise by the Royal Marines in decades.
It comes amid escalating Russian aggression towards Europe, with Cold War levels of submarine activity reported in the Northern Atlantic and frequent air incursions on UK airspace.
And since Putin’s Novichok attack on former spy Sergei Skripal and his daughter Yulia in Salisbury last year, tensions between London and Moscow have been on a knife-edge.
Harry, dubbed “H” by the Marines, will fly from RAF Brize Norton in Oxfordshire to Norway in the coming weeks.
The prince, expecting his first child with 37-year-old wife Meghan, will be taken to a remote base to join British troops from 42 Commando, American, Dutch and Norwegian combat marines.
Including forces from the US and Europe, 8,000 soldiers will be involved.
Royal Marines started travelling to Norway on New Year’s Day from their base at Bickleigh Barracks in Devon.
The country, along with Finland and Sweden, is on Europe’s front line against Russia and is a potential site of an invasion by Moscow.
During the exercise, special forces will be parachuting or travelling in by boat.
Light-armoured Marine vehicles will move in, there are expected to be mortar, rocket, artillery and anti-tank attacks and Marines will ski into action.
Accomplished skier Harry will be given every access to all areas of the designated battleground.
Over several days he will be briefed at every stage of the “battle” which will include special forces and commandos spearheading a retaliation against Russian attack.
The troops are expected to hold the Northern Flank until British and US reinforcements arrive.
Harry’s involvement is not due to be officially announced and the Mirror has agreed not to publish sensitive details of his movements.
The prince took on the role of Captain General of the Royal Marines from Prince Philip in December 2017 after he retired as a frontline Apache pilot.
In Afghanistan, Harry worked closely with Marines from 40 Commando. He has killed Taliban fighters and an insurgent commander revealed they had planned to kidnap Harry.
The Royal Marines’ new role as the lead element of Britain’s Joint Expeditionary Force puts them in the front line in any potential miliary conflict with Russia.