British troops train for war with Russia from the London Underground

British soldiers are fighting a Russian invasion from a platform on the London Underground in a wargame that reveals the UK must invest much more in defence - or risk defeat.

In the scenario, the year is 2030, and the troops are part of a UK-led NATO headquarters that has rapidly deployed to Estonia after Russian troops attacked the Baltic states in the opening salvo of what could become World War Three.

The British forces and their allies, including soldiers from the United States, have turned a disused part of Charing Cross Tube station into a makeshift underground base that they are imagining is in the Estonian capital of Tallinn.

It is an example of how civilian infrastructure can be requisitioned for military use in a time of war.

From here, they hunch over laptops and study large screens, drawing on Artificial Intelligence and other forms of digital technology to help identify Russian targets at speed, before launching swarms of drones, missiles and jamming equipment to destroy them.

The battle seems to go well - but the troops are relying on computer codes that are not yet integrated across the British military and weapons that have not yet been bought.

Commanders do not even know if the government will give them the billions of extra pounds in funding that they are understood to need to purchase this kit in sufficient volume.

In the wargame, the UK-led side must field more than 5,000 drones daily - both for attacking and surveillance - to stand a chance against a Russian force that is battle-hardened and resilient after years spent fighting against Ukraine.

Many of the drones would be single-use, requiring vast stocks of additional aircraft to replenish the frontline and an industrial base that can generate hundreds of thousands more.

This is something the Ukrainian military and its industry partners are doing today for real.

By contrast, however, it is understood that the British army right now would only be able to deploy hundreds of drones a day - and even that tempo could not be sustained for long because its stockpiles are so small and production lines across UK industry are yet to be geared up for the scale of manufacturing that would be required in a real war.

Lieutenant General Mike Elviss, commander of the Allied Rapid Reaction Corps (ARRC) - the name of the UK-led NATO headquarters involved in the exercise - articulated the challenge in a video message that was played to Sky News and a group of other journalists that was invited to watch some of the simulation at Charing Cross station on Wednesday.

"The scenario you are about to see is very deliberately set in 2030 because that is where we see the threat from Russia to be at its most acute," he said.

"It's also when we could realistically deliver the modernised technology and increased readiness required to meet that threat, but only with the right investment now, and with the support of industry to build a national arsenal, not just of munitions stockpiles - although that's critical - but also of the national means of production that can scale in wartime.

"There is huge opportunity here, but peril if we ignore the risk."

A failure by Sir Keir Starmer's government to finalise a major investment plan for defence - that should have been published last autumn - has already hampered the ability of the army, Royal Navy and Royal Air Force to rearm at the pace that many believe is necessary.

John Healey, the defence secretary, said this week that the Defence Investment Plan would be out soon.

But its publication is only part of the challenge.

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The Treasury is reportedly expected to agree to give the Ministry of Defence an additional £18bn over the next four years to help fund the rearmament, but that sum of money is far short of what the military requires to be ready for a potential war with Russia by 2030.

Before accessing a disused platform on the London Underground via a steep flight of stairs in between two frozen escalators, the group of visiting journalists at Charing Cross station was shown a pretend television news report entitled "World At War".

A mock on-screen presenter set the scene, describing how Russian troops have just attacked Estonia, Latvia and Lithuania.

The invasion prompted NATO allies to trigger Article 5 - the alliance's founding principle, which means an attack on one member state is deemed to be an attack on all.

UK forces in the ARRC have moved to Estonia from where the headquarters, which would comprise some 500 personnel from more than 20 allied nations if deployed for real, is tasked with commanding a Corps of up to 100,000 troops from across NATO.

In the exercise, just over 100 military personnel are spread out along a train platform in both directions and across the inside space that connects them - a familiar setting for anyone who has ever been on the London Underground but a very unusual place to find soldiers.

Such a location is ideal for a military headquarters, though, because it is buried deep underground, making it hard for Russia to locate and destroy.

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The clear articulation in the scenario of Moscow as the enemy is different to other NATO exercises where the opponent is typically an unnamed entity that participants know with a nod and a wink is meant to represent the Kremlin.

As the battle unfolds, commanders share information and discuss a plan to target a Russian position.

They liaise with other military personnel who have deployed for real to Estonia.

The visiting journalists are asked to don virtual reality headsets to see the attack play out, with the UK and its allies - coloured in blue - using drones, fast jets and rocket systems to take out what had been deemed a valuable Russian target, which was coloured in red.

Fake explosions illustrate successful hits.

In the small section that we watched, the Russian forces did not strike any British targets.

But this wargame is taking place across the whole week, creating a lot of opportunities for soldiers to better understand their own weak points and what needs to be done to fix them.

(c) Sky News 2026: British troops train for war with Russia from the London Underground