NATO has revealed plans for its largest military exercises since the end of the Cold War that will see 32 countries prepare for a Russian attack.
Steadfast Defender 2024 is now underway across thousands of miles of Europe as armadas, fighter jet fleets and 90,000 troops conduct land, sea, air, cyber and space operations.
In a sobering Nato briefing today, Assistant Chief of Staff of Supreme Headquarters Allied Powers Europe (SHAPE), Brigadier General Gunnar Bruegner said the "clock is ticking".
Without mentioning Russia by name, he said Nato must prove it is "ready" for any threats to its security.
"Every exercise matters....the biggest picture is deterrence," the military chief added.
Bruegner's statements come amid a flurry of recent warnings from top military chiefs and policymakers over the threat of full-scale war with Russia in the coming years.
And so it is fitting that Nato is kicking off its largest military exercises in decades - based on its "new defence plans" for Europe.
It will see alliance members rehearsing how US troops could reinforce European allies on the alliance's eastern flank if a conflict were to flare up with a "near-peer" adversary.
Some 20,000 British troops will join its key allies in the war drills which will continue through to May and include 31 alliance members and Nato candidate Sweden.
The Royal Navy's two new aircraft carriers and eight warships will also be sent out to stage and test conflict scenarios in naval drills named "Joint Warrior".
US paratroopers will later swoop in across eastern Europe as part of the "Swift Response" drill, while thousands of troops will stage battles across on Poland and into the Baltics for "Dragon-24".
More than 50 ships from aircraft carriers to destroyers will take part, as well as more than 80 fighter jets, helicopters and drones and at least 1,100 combat vehicles including 133 tanks and 533 infantry fighting vehicles.
The plan behind Steadfast Defender 2024 (STDE24) is to "promote readiness across the strategic, operational and tactical level," Brig Gen Bruegner said.
He added: "The sheer size and ambition of this exercise will show us where we are and how we need to adapt."
One that will send a "clear message inside and outside the military [alliance] that we are ready!"
It's an opportunity to carry out "stress-testing from the top to the bottom," Bruegner said.
"This is how we prepare ourselves, stress this with troops on ground and build capacity towards deterrence."
Only last week, The Sun joined crack Royal Marines training for war with Russia at their new arctic base Camp Viking in Norway.
We swooped into the frozen outpost on board a Commando Force Merlin helicopter before roaring over icy wastes on camouflaged snowmobiles.
The elite commando force will be helping to spearhead Britain's ground operations during Steadfast Defender.
Speaking to The Sun at the arctic base, Armed Forces Minister James Heappey explained that if Nato went to war with Russia, Britain’s main role would be fighting in Arctic conditions, which are the toughest in the world.
The planned war games will be performed close to Russia's borders in key areas including the Baltics and close to the new WW3 flashpoint, the Suwalki Gap.
The 60-mile Polish-Lithuanian corridor - which connects Belarus to Russia's western enclave of Kaliningrad - has been dubbed Nato's "weakest link" as it's feared to be a future battleground for a Russia-Nato war.
For the West, it is the only land link to the three ex-Soviet Baltic republics - Lithuania, Latvia and Estonia - which would be left vulnerable to Putin if the west lost control of the gap.
It comes as last weekend, a damning new report detailed how the UK's military is not prepared for a full-blown war with Russia.
The "overstretched" British armed forces would only last a "couple of months" and are "far below the level required to counter with certainty a threat from the Russian Army," MPs warned.
