A vision of what war between the UK and another state such as Russia would look like is sketched out briefly but starkly on a page of the strategic defence review.

Such a conflict could involve attacks on the armed forces in the UK and overseas, air and missile attacks on critical infrastructure, and sabotage and efforts to manipulate information and undermine social cohesion.

Britain is “already under daily attack” in cyberspace with 89 “nationally significant” attacks in the year up to last September, according to the review, which calls for a response to a “a new era of threat”, underlined by, but not limited to, increasing Russian aggression.

After years in which UK defence was shaped by the post-cold war era, when opponents were mainly non-state actors, the review says Britain must be ready to once again “fight and win” a full-scale war.

Sixty-two recommendations are put forward by its authors: the former defence secretary and Nato chief Lord Robertson, the retired British army general Sir Richard Barrons and Dr Fiona Hill, a Russia expert and former White House adviser.

They write that they are confident that the transformation they propose is affordable over 10 years, but caution: “As we live in such turbulent times it may be necessary to go faster. The plan we have put forward can be accelerated.”

Nuclear weapons

Russia’s reliance on “nuclear coercion” will be “the central challenge” for the UK and Nato allies in the coming decades, the review warns.

The defence secretary, John Healey, announced that the government would “secure the future” of Britain’s nuclear deterrent by investing £15bn in the UK nuclear warhead programme.

For the future, the report indicates that Britain should expand its ability to launch a devastating nuclear strike by means other than its submarine fleet alone, referring to “strengthening extended deterrence”.

While there are different options, the review says there will be a need over the coming decade for more F-35 fighter jets, a variant of which can carry nuclear bombs.

At the same time, the review calls for a “national endeavour” public communications campaign to convince the general public of what it describes as “the necessity” of the nuclear deterrent.

Personnel

There should be “a small uplift in troop numbers”, according to the review in a recommendation that might not quite put to bed years of angst about Britain’s “shrinking” army.

The army should be a mix of regular and reserves, it recommends, with a minimum of 100,000 soldiers, of which 73,000 should be regulars.

In terms of recruitment, it calls for a focus on speed alongside a more flexible approach to fitness standards and new recruits being able to pass through medical and bureaucratic checks within a much shorter time than the current six months.

Britain should also borrow from Australia’s military “gap years”, based on thinking that women and people from black and minority ethnic backgrounds are less likely to be put off if there is a 12-month option of engaging with the military.

Society and the home front

Cadet forces in schools and communities across the UK should be expanded by 30% by 2030, according to the review, with an ambition to reach 250,000 in the longer term and a greater focus on cadets developing Stem skills.

This would be part of a broader move to “reconnect” defence with society, something Keir Starmer has already sought to do.

However, the review envisages two years of public outreach events to talk about threats and the rationale for defence investment, and work with the Department for Education “to develop understanding of the armed forces among young people”.

Greater focus is needed on protecting the UK’s critical national infrastructure from attack, the review says, calling for plans to be drawn up by December 2026. Part of this could include the development of a new reserve force.

Healey has meanwhile committed up to £1bn of funding to enhance missile defence to protect the “UK homeland”.

Army, navy and air force

Starmer used the launch of the review to commit to building “up to” 12 new conventionally armed, nuclear-powered submarines to replace Britain’s seven-strong Astute class from the end of the next decade onwards.

However, the review says the Royal Navy “must continue to move towards a more powerful but cheaper and simpler fleet”. It envisages the navy playing a new role in securing the UK’s critical undersea infrastructure and maritime traffic.

Its transformation should include use of unmanned technology across the board, including a “hybrid” aircraft carrier air-wing with both crewed aircraft and drones.

The army must deliver “tenfold increase in lethality” at the same time as re-equipping and modernising after much of its kit, including Challenger 2 tanks and ammunition, have been given to Ukraine.

A new “digital warfighter group” – using AI and drones – should be established by July 2026.

Cyber and intelligence

While the UK is “already under daily attack” in cyberspace, the review warns that cyber-threats will become harder to mitigate as AI and other technology evolves.

The formation of a new “cyber and electromagnetic command” to oversee cyber-operations was announced last week by the MoD. That new command must be filled by civilians and reserves, given that greater expertise exists in the civilian sector, according to the review.

While the review says the UK has access to world-class intelligence capabilities, they are “underpowered and fragmented” within defence intelligence, part of the MoD, and there should be a new unit to protect the military from hostile spy services.

The threats

At the apex, Russia is described in the review as “an immediate and pressing threat”.

While Ukraine has temporarily degraded its land forces, the review warns that Russia will be able to rebuild in the event of a ceasefire there

Different language is used for China, which is described as a “sophisticated and persistent challenge”, which has embarked on a large-scale military modernisation that includes the development of missiles that can reach the UK.

Others named include North Korea and Iran, both of which continue to be a direct threat to the UK in cyberspace.

In addition, the report cautions: “It will be important to scan for new threats, including those from ‘middle powers’ that may be hostile to UK interests.”