‘Testing the refreshed government War Book’ as UK prepares for landmark defence exercise

Britain will stage its largest home defence exercise in decades in 2027, testing how effectively the Government can respond to hybrid attacks and putting its updated national emergency planning framework to the test.

Exercise Albiston Shadow will involve ministers and officials from across government and is intended to strengthen national resilience against threats that could disrupt critical infrastructure, public services and national security.

The details were confirmed in a parliamentary written answer after Stuart Anderson, Conservative MP for South Shropshire, asked what preparations were under way.

Louise Sandher-Jones, Minister for the Armed Forces, said the Ministry of Defence was working closely with the Cabinet Office, which will lead the exercise.

“ALBISTON SHADOW will be the largest UK Home Defence exercise in decades, and will involve ministers and officials from across Government,” she said.

She described the exercise as an important step in improving national preparedness, adding that it would test the Government’s response to hybrid attacks through the refreshed Government War Book.

The War Book provides a framework for government planning and responding to major national emergencies. Its revision forms part of an accelerated Home Defence Programme led by the Cabinet Office.

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Sandher-Jones said the Ministry of Defence would participate fully, with preparations already under way alongside the Cabinet Office to design and plan the exercise.

Darren Jones, Chief Secretary to the Prime Minister, announced the planned exercise in July in the Government’s first Annual Statement on National Resilience.

In September, Sandher-Jones said the War Books would be rewritten by the end of this year.

The exercise comes as concern grows over the range of threats facing Britain, including cyber attacks, hostile activity against critical infrastructure and attempts by foreign states to undermine national security without resorting to conventional military action.

Albiston Shadow is intended to test whether government departments can coordinate effectively under pressure. Its scale reflects the growing recognition that defending the UK requires not only military capability, but also the ability of the state to withstand and respond to disruption at home.

This comes as the UK is facing a growing campaign of hybrid warfare, with hostile activity increasingly reaching beyond the battlefield and into the infrastructure, businesses and everyday lives of ordinary citizens.

Cyber attacks, threats against undersea cables and security scares involving commercial airlines are among the incidents highlighting the vulnerability of a country whose economy and national security depend on interconnected systems.

Unlike conventional warfare, hybrid attacks are designed to create disruption, uncertainty and fear without necessarily triggering an outright military response. They can exploit weaknesses in digital networks, transport systems, energy supplies and communications infrastructure, allowing hostile states to exert pressure while maintaining a degree of deniability.

The threat to undersea cables is particularly serious. These networks carry much of the world’s international data traffic, connecting financial markets, businesses, governments and individuals. Damage to critical cables could disrupt communications and economic activity, while making it harder for the UK to maintain reliable links with allies and international markets.

Russia has been associated with threats and activity directed towards critical undersea infrastructure. The concern is not simply that cables could be damaged, but that their vulnerability could be exploited to intimidate governments and test how quickly the UK and its partners could respond.

Cyber attacks present another front. Government departments, businesses and essential services increasingly rely on digital systems that can be targeted remotely. Even when an attack does not cause lasting damage, the disruption can undermine public confidence, interrupt services and impose substantial financial costs.

The aviation sector has also faced security scares, including airlines being forced to land following bomb threats. Such incidents demonstrate how relatively low-cost threats can generate significant operational disruption, divert resources and create anxiety among passengers.

Taken together, these developments illustrate the changing character of national security. Britain does not need to be struck by missiles or invaded by troops to experience the consequences of hostile action. Its transport networks, digital infrastructure and communications systems can all become targets.

The challenge for the Government is to recognise that these incidents are not isolated security problems. They form part of a wider environment in which hostile states can probe vulnerabilities, disrupt essential services and test national resilience.

Protecting Britain therefore requires more than military strength. It demands stronger cyber defences, surveillance of critical infrastructure, closer cooperation with allies and the ability to respond quickly when threats emerge.

Hybrid warfare is not a distant possibility. It is a present-day security challenge, and Britain must prepare for the possibility that the next attack may arrive not through its borders, but through the systems on which the country depends.