Around 8,000 British Army troops will take part in exercises across eastern Europe to combat Russian aggression, as part of what is described as one of the largest deployments since the Cold War.
Hardware will also be deployed to countries ranging from Finland to North Macedonia this summer under plans that have been enhanced since the invasion of Ukraine.
Defence Secretary Ben Wallace said the "show of solidarity and strength" will see UK service personnel joining with NATO allies and those from the Joint Expeditionary Force (JEF) security coalition for the exercises.
The following pieces of kit will be sent across the continent:
- 72 Challenger 2 tanks
- 12 AS90 tracked artillery guns
- 120 Warrior armoured vehicles
The Ministry of Defence (MOD) said the action had been long-planned, but that it had been enhanced since Russia invaded its neighbour in late February.
Aircraft, tanks, artillery and armoured assault vehicles will join the exercises across Europe, with UK troop numbers expected to build to a peak of around 8,000 personnel operating between April and June.
Commander Field Army Lieutenant General Ralph Wooddisse said: "The UK makes a significant contribution to the defence of Europe and the deterrence of Russian aggression.
"The British Army's series of exercises is fundamental to both.
"The scale of the deployment, coupled with the professionalism, training and agility of the British Army, will deter aggression at a scale not seen in Europe this century."
Speaking to Forces News, retired General Sir Richard Barrons said an increased NATO and UK presence is necessary - estimating the number of Russian soldiers on the ground in Ukraine to be 80,000.
Interoperability must be at the heart of alliance efforts in the region, he added, to "maximise the power of our collective efforts".
Watch: What is the Joint Expeditionary Force?
Mr Wallace said: "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."
Troops from B Squadron of the Queen's Royal Hussars deployed to Finland this week to take part in Exercise Arrow. They will be embedded into a Finnish Armoured Brigade, with participation from other partners including the US, Latvia and Estonia.
The exercise will aim to improve the ability of UK and Finnish troops to work alongside each other as part of the JEF, deterring Russian aggression in Scandinavia and the Baltic states.
In May, the Royal Welsh Battlegroup and the Royal Tank Regiment will participate in Exercise Hedgehog on the Estonia-Latvia border.
They will be alongside 18,000 NATO troops, including French and Danish who are part of the British-led NATO enhanced Forward Presence in Estonia.
Hedgehog is the biggest military exercise in Estonia and takes place every four years.
Watch: UK and NATO must 'resurrect scale' with eastern Europe presence
Exercise Defender in Poland will be held until late May.
It will see 1,000 soldiers from the King's Royal Hussars Battlegroup and C Squadron of the Light Dragoons deployed alongside troops from 11 partner nations including Poland, Denmark and the US.
The training will involve Challenger 2 tanks and other armoured vehicles deploying from the NATO Forward Holding Base in Sennelager, Germany.
The deployment will be supported by 104 Theatre Sustainment Brigade operating from the UK and in bases in Europe.
Exercise Swift Response
Exercise Swift Response began this week and sees elements of 16 Air Assault Brigade Combat Team and 1 Aviation Brigade Combat Team operate alongside French, American, Italian and Albanian counterparts in North Macedonia.
There are 4,500 personnel taking part in the training, including 2,500 British troops.
The exercise involves parachute drops, helicopter-borne air assaults and sees a company of French paratroopers integrated into the 2 Parachute Regiment Battlegroup and an Italian battlegroup working to a British chain of command.
Meanwhile, the UK will also be deploying a major headquarters to the Baltic region in support of the JEF. It will be the Standing Joint Force HQ's first operational deployment.