Around 8,000 British soldiers are due to be sent to eastern Europe to take part in military exercises designed to combat 'Russian aggression'.
The deployment - which is one of the largest to take place since the Cold War - will see troops placed in countries from Finland to North Macedonia.
Dozens of tanks and more than 100 armoured fighting vehicles will also be sent to the locations this summer under plans that have been bolstered since the war in Ukraine began.
The armed forces will be joined by tens of thousands of troops from NATO and Joint Expeditionary Force allies, which include the likes of Denmark, Iceland and Norway.
The Ministry of Defence (MoD) said the planned exercises will improve the ability of UK and Finnish troops to work alongside each other, "deterring Russian aggression in Scandinavia and the Baltic states".
Defence Secretary Ben Wallace said the move will show "solidarity and strength".
"The security of Europe has never been more important. These exercises will see our troops join forces with allies and partners across NATO and the Joint Expeditionary Force in a show of solidarity and strength in one of the largest shared deployments since the Cold War," he said.
"Operating across Europe, the British Army will stand alongside partners, combining our capabilities and shared values, promoting peace and security."
The UK deployment is expected to build to a peak of around 8,000 personnel operating in mainland Europe between April and June.
Some of the exercises are set to involve parachute drops, helicopter-borne air assaults Challenger 2 tanks.
The drills aim to "showcase the scale and significance of the British Army's contribution to the defence of Europe", the MoD added.
