Britain will send 20,000 service personnel to one of Nato’s largest military exercises since the Cold War, as the alliance practises repelling an invasion by Russian President Vladimir Putin’s forces.
Defence Secretary Grant Shapps will announce the deployment of Army, Navy and RAF members to the 31-nation drill across Europe during a speech in London on Monday.
He will say the contribution to the Steadfast Defender exercise will provide “vital reassurance against the Putin menace” as he warns the West stands at a “crossroads”.
The war games come after ministers announced a further £2.5 billion support package to Ukraine and the RAF airstrikes, with the US, on the Houthis in Yemen.
Mr Shapps will set out his vision for how the UK will deter threats, as allies remain concerned about the threat posed by Mr Putin as his war approaches its second year.
In the Lancaster House speech, Mr Shapps is expected to say: “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.”
Some 16,000 troops with tanks, artillery and helicopters will be deployed from the British Army across eastern Europe starting next month as part of the exercise.
The Royal Navy will deploy more than 2,000 sailors across eight warships and submarines, while more than 400 Royal Marines Commandos will be sent to the Arctic Circle.
The RAF will use F-35B Lightning attack aircraft and Poseidon P-8 surveillance aircraft.
Defence sources said that the exercise will prepare for the invasion of a member state by any aggressor, with the main threats being considered to be from Russia and from terrorism.
Labour backed the commitment of UK forces to Nato, but said Mr Shapps’s speech was “little more than PR spin”.
“Grant Shapps is reheating old announcements from other people,” a party spokesman said.
“The PM confirmed 20,000 UK troops will exercise in Europe three months ago, while Nato released details of Steadfast Defender four months ago.”
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