Both the Strategic Defence Review (SDR) and National Security Strategy (NSS) are unequivocal that the United Kingdom (UK) could become embroiled in a peer conflict in the near future. The post-Cold War ‘peace dividend’ has given way to an increasingly confrontational geopolitical environment, in which adversarial nations – chief among them the so-called ‘CRINK’ states of the People’s Republic of China (PRC), Russia, Iran and North Korea – pose a growing threat to British interests.
Russia’s brazen aggression towards European nations – including drone incursions, cutting undersea cables and targeting space assets – could easily spiral into open conflict. In December 2025, Mark Rutte, Secretary General of the North Atlantic Treaty Organisation (NATO), warned the alliance that it should prepare for an attack by Russia within five years. Sir Keir Starmer, Prime Minister, stated at the Munich Security Conference that ‘we must build our hard power, because that is the currency of the age.’ With the UK being a key nation within NATO, for this week’s Big Ask, we asked seven experts: Should Britain prepare for war?
Dr Sophy Antrobus, Baroness Antrobus MBE
Co-Director and Senior Research Fellow, Freeman Air and Space Institute, King’s College London
The short answer is yes. In a volatile and unstable world, with adversaries who are already attacking the UK – not yet with missiles, but by other means – the only way to deter war is to prepare for it. As ACM Sir Richard Knighton, Chief of the Defence Staff, said last December: ‘the situation is more dangerous than I have known during my career, and the price of peace is rising’.
Preparation will require more engagement with the public – not to scare, but to inform. Recent polling showed that three-quarters of Britons consider it important to strengthen both the UK’s hard and soft power, including approximately four in ten who rate it ‘very important’. Yet, only a minority favour tax increases or spending cuts to fund greater spending on the British Armed Forces.
The SDR stated that the UK must ‘increase national warfighting readiness’, and that this needs to happen urgently. Communication and preparation of the nation requires political will to level with the public, with recent comments from British ministers suggesting that this is understood inside the Ministry of Defence (MOD).
Getting the conversation going more broadly across His Majesty’s (HM) Government and the country is now crucially important. The UK can learn from its Scandinavian allies: Denmark established a Ministry of Resilience and Preparedness in 2024, and Sweden distributed its brochure ‘In Case of War’ to its population the same year.
If Britain fails to prepare, it will embolden its adversaries further. That is my greatest fear.
Neil Brown
Honorary Fellow, Council on Geostrategy, and Organising Committee Member, London Defence Conference
If one listens to what every modern British prime minister has said, the first responsibility of government is to safeguard the nation. This is not a hard question. The UK should always be prepared for war.
This is not the case. It has not been so for some time. There is no good excuse.
Wanton disinvestment in defence capabilities since the end of the Cold War ignored an already worsening geopolitical outlook. Threat-based planning assumptions, published throughout the Cold War but suddenly withheld on the grounds of security, hid gaps in warfighting and strategic readiness that have only grown.
In this increasingly dangerous world, preparing for war should be the first priority of HM Government. Given the cost of failing to deter or losing a major war, there are no good reasons to delay what needs to be done; not the scale of the reinvestment needed in the British Armed Forces and defence industrial base; not an economy saddled with high public debt and anaemic growth; not even a population inured to risk.
Today’s political leaders cannot claim ignorance of the danger. Today’s military leaders cannot continue to be so accepting of whatever hand is dealt by HM Treasury.
The SDR’s recommendations should be implemented urgently to deter adversaries, reassure allies and restore the UK’s credibility and influence. Plugging the defence funding ‘black hole’ is low-hanging fruit in the context of the British economy. Committing to spending 3.5% of Gross Domestic Product (GDP) on defence long before the end of the next Parliament is the pretext for credible national preparation.
Senior Lecturer in Post-Soviet Security, Department of War Studies, King’s College London
The UK has no choice but to prepare for war if it wants to protect itself against both current and future threats. Since 2022, Vladimir Putin, President of Russia, has made the idea of existential conflict with free and open nations central to his presidency. Britain is a particular target of Kremlin hate, now that the Trump administration has partially aligned the United States (US) with Russia.
That is not going to change when the conflict in Ukraine ends, although the manner of its end will shape the future threat – a Russian defeat in Ukraine would be the best protection for the UK and the rest of Europe.
With an intensely hostile and aggressive Russia, and an unreliable US, Britain needs to act quickly to counter growing threats to Critical National Infrastructure (CNI) and other sub-threshold attacks, and to prepare for the possibility of military conflict. This will require two things.
Firstly, the UK needs to get serious about defence spending. That means politically difficult tradeoffs for HM Government. Opposition parties who support enhancing British defence will need to get behind this, and not seek to exploit it.
Secondly, even with dramatically increased spending, the UK will not have the resources to stand alone, nor would it be strategically desirable. Britain should work with its European partners to strengthen defence cooperation and maximise European autonomy. Whether the sense of urgency is great enough in Westminster to push these changes through however remains to be seen.
Professor of War Studies, Loughborough University
To argue that the reality of international relations is currently fraught would be an understatement. Having moved from the sunny uplands of the post-Cold War peace dividend, the unipolar moment and the vision of bloodless war as in Kosovo, the last 25 years have proven, as Colin S. Gray thought they would, to be the beginning of ‘another bloody century.’
The failures in Afghanistan and Iraq, followed by the disappointments of the Arab Spring, have cast long shadows over contemporary politics. Even now, the Americans and the Iranians wrestle with a ‘nuclear’ deal, with the US’ military might poised for a potential strike. The White House of Donald Trump, President of the US, has not been shy in its use of force, as events in Venezuela proved not coy about its ambitions to protect and dominate the Western Hemisphere, even if that means threatening to invade a NATO ally over Greenland.
All of this comes while the US is lecturing European states, including the UK, on the deficiencies in defence spending, (alleged) combat reluctance and a lack of understanding of the realities of current geopolitics.
The reaction of Britain has (finally) been an appreciation of the limits of the ‘special relationship’, the realities of a Washington elite with a profoundly different view of the Russia question, and the challenge of balancing trade with the PRC and Beijing’s obvious ambitions, which run from the Arctic to Antarctica. While politicians mull over their choices, scholars ponder the lessons of Munich.
The UK needs to prepare for all possibilities, which include a serious reconsideration of its deterrence posture, its ability to defend British interests and its role in securing the balance of power in Europe – in short, a renewed British way of war.
Adjunct Fellow, Council on Geostrategy
The UK is already at war. It is backing Ukraine and shares its aim: to destroy Russia’s will and means to fight. The Kremlin’s declared aim is to shatter NATO, which is the centre of gravity of Britain’s national security. The UK is experiencing a spate of hard sub-threshold attacks on industry, public services and CNI. So, the time for ‘preparing’ should be over.
Yet, the crucial conversations with civil society have barely begun, and Britain is rearming far too slowly for the potentially sudden increases in aggression that might occur once Russia itself recovers and modernises its conventional military.
The biggest step-change should occur in the security and political elite’s appetite for risk. Catastrophic failure should be the nightmare that haunts everybody, from HM Treasury and the Bank of England through to council leaders and community leaders. There are still too many people who have never asked themselves what the UK would need to do to win a war.
Postdoctoral Fellow, Finnish Institute of International Affairs (FIIA)
As global security continues to deteriorate, Britain must be ready to fight to defend its interests and those of its European allies from Russian aggression. In defence policy, HM Government has honoured its Brexit promise to remain a power guaranteeing security in Europe. Either minilaterally or through NATO, the UK is a linchpin for wider defence cooperation in Northern Europe.
This responsibility will only increase if the Trump administration withdraws more American forces and enablers from NATO’s eastern flank. Britain leads the NATO Forward Land Forces (FLF) battlegroup in Estonia, regularly reinforces significant cold weather exercises with Nordic militaries and is key to NATO cooperation in the Arctic. Utilising these frameworks to maintain credible deterrence, HM Government should continually signal an astute readiness for crisis response.
The UK’s leadership is welcome in Northern Europe, but it remains questioned in the region whether Britain is too stretched between European commitments and military contributions elsewhere. Nordic and Baltic capitals are disappointed that the UK’s defence investment is not quite where it should be; that Britain’s military depth is hindered by recruitment and retention problems in its armed forces; and that domestic political instability weakens its strategic focus.
Resolving these difficulties while prioritising the UK’s military resources to cover considerable defence commitments on NATO’s front line will ensure Britain’s future as a primary security guarantor in Europe.
Freelance columnist, Daily Telegraph, and ex-commander, Royal Navy
The UK should prepare for war, not because it fears it is likely in the next five years from Russia, or from anyone else, but because doing so makes it less likely. The post-Cold War peace dividend was spent under-resourcing defence based on an arrangement with the US which assumed that it would provide the deterrence and the hardware for Britain. Now, both that assurance and the stability it created are diminishing.
If the two first principles of government are security and prosperity, a well-founded and thriving defence industry touches both. Defence is no longer an either/or option, and as a notion should be embraced, not shied away from. This would not only physically improve the UK’s resilience, it would create an awareness that would do the same at a cerebral level. Britain has recently gone soft on what war and national survival means. This would address that issue.
Saying that ‘hard power is the currency of our age’ is fine, but it does then need actual currency to back it. There is no sign of this yet, just more tough talk and soundbites. One can understand why the UK did not invest properly in defence for the last 40 years – wrong and short-sighted, but forgivable.
Now, it is not. Reversing this trend would make Britain more secure, more resilient and reduce the likelihood of a war – which would be catastrophically more expensive. 2022 was the obvious time to do this. The second-best time is now.
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The unanimity of the above well-informed individuals that the UK needs to rearm fast to deter Russian aggression contrasts starkly with the general mood music from our politicians, who soothe the public with silence, rather than informing them of the reality and immediacy of the actual risks facing the UK.