20,000 British troops will be deployed in Europe alongside Nato forces in an attempt to bolster global security.
In a speech today, Defence Secretary Grant Shapps set out plans for the UK to respond to the end of the so-called 'peace dividend' enjoyed by the West since the end of the Cold War.
This comes just days after the Government authorised strikes on Houthi rebels in Yemen and unveiled a further £2.5bn UK support package to Ukraine.
The 20,000 troops will be deployed across Europe in the first half of this year as part of Exercise Steadfast Defender 24.
Shapps is expected to warn that the "foundations of the world order" are being "shaken to their core"
PA
Shapps warned that the "foundations of the world order" are being "shaken to their core", arguing that Britain "must be prepared" to deter its enemies.
The deployment of 20,000 troops will help to support "one of the largest NATO deployments since the Cold War", Shapps said.
Some 16,000 of them will be troops from the British Army, deployed across eastern Europe from February to June 2024. They will be supported by British taking tanks, artillery, helicopters, and parachutes.
Giving a speech at Lancaster House today, Shapps is said: "We are in a new era and we must be prepared to deter our enemies, prepared to lead our allies and prepared to defend our nation whenever the call comes.
“Today our adversaries are busily rebuilding their barriers. Old enemies are reanimated. Battle lines are being redrawn.
"The tanks are literally on Ukraine’s lawn. And the foundations of the world order are being shaken to their core. We stand at a crossroads.
"I can announce today that UK will be sending some 20,000 personnel to take part in one of NATO’s largest deployments since the end of the Cold War. Exercise Steadfast Defender.
"It will see our military joining forces with counterparts from 30 NATO countries plus Sweden, providing vital reassurance against the Putin menace."
Overnight on Friday, Britain joined the US in unleashing targeted strikes against military facilities in Yemen in response to the "reckless actions" of Houthi rebels in the region.
Action was taken after weeks of disruption to international shipping in the Red Sea.
The rebels had launched a series of attacks on shipping routes in the Red Sea, which they claimed to be a show of support for Palestine and terror group Hamas.
Houthi officials have reacted with fury to the UK and US' response, calling the strikes "barbaric".
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The US Air Force said American and British forces struck more than 60 targets in 16 locations.
The MoD said "particular care was taken to minimise any risks to civilians” when planning the strikes on Houthi targets in Yemen.
The Cabinet was informed of the plans in a meeting called last night by No10. In an unusual move, the Government also briefed Sir Keir Starmer and shadow defence secretary John Healey.