How can Britain work with its allies and partners to boost its defence posture?
The Big Ask | No. 24.2025
The Strategic Defence Review (SDR), published last week, devotes 10% of its length to allies and partners, with focuses on the United States (US), North Atlantic Treaty Organisation (NATO) allies in Europe, Ukraine, and allies and partners beyond the Euro-Atlantic – including AUKUS, the Five Eyes agreement and initiatives in the Indo-Pacific region. It acknowledges that ‘Alliances and partnerships are the bedrock of global stability’, advocates a ‘NATO First’ policy and underscores the importance to the United Kingdom (UK) of forming and maintaining cordial geostrategic relationships.
As the geopolitical order becomes ever more multipolar and volatile, and with the NATO Summit being held at the end of June, the importance of strong alliances and partnerships continues to increase. With the growing emphasis on minilateral and multilateral groupings to bolster defence and deterrence efforts, for this week’s Big Ask, we asked five experts: How can Britain work with its allies and partners to boost its defence posture?
Deputy Director (Geopolitics), Council on Geostrategy
As was noted in the SDR, the UK needs to bolster its defence industrial base collaboration with the US, working to bolster capability in Europe and in the Indo-Pacific.
In terms of the US, this already robust relationship might be put on a firm footing in a bilateral agreement, something along the lines of the Lancaster House agreement with France or the Trinity House agreement with Germany. This should include continued investment and innovation in each other’s defence markets – perhaps under the National Technology and Industrial Base (NTIB) carve-out – but should also include frameworks for cooperation and leadership in other markets, such as Europe and the Indo-Pacific. The two powers might establish an annual Defence Industrial Base (DIB) 2+2 to coordinate a strategic approach towards those two regions.
For example, Britain might develop a defence industrial strategy which continues to prioritise integration technologies in NATO, while also supporting US equipment and market integration efforts in the Indo-Pacific. Given British and American standards leadership in NATO, they might drive shared standards across concepts of operation, perhaps starting with the Indo-Pacific Four (Australia, Japan, New Zealand and South Korea) in an effort to support deterrence. They could also encourage regulatory harmonisation more broadly in larger forums, such as the Partnership for Indo-Pacific Industrial Resilience (PIPIR).
Finally, the UK needs to work closely with the US and Australia on AUKUS Pillar II. There is a real danger that current pressures on Pillar I – the American review of the US Virginia class element of AUKUS – will weaken the fabric of the broader agreement. At present, there is precious little to show for all the years of work done in the name of Pillar II. Britain must help support – or even lead – reform of the way that Pillar II is organised, and seek to make instrumental changes in driving common requirements under a common budgetary process, which would then drive real-world contracts.
Former Chairman, Joint Intelligence Committee, and former Ambassador of the United Kingdom to Germany
The future post-Ukraine, post-Trump strategic environment will require major changes, both in the size and quality of the British Armed Forces and how the UK cooperates with its allies. Two suggestions for action which Britain should take to help bring this about are as follows:
Firstly, NATO should remain the basis of the UK’s defence relationship with its European partners, and should shape the military headquarters through which this relationship is, in practice, organised. But they cannot survive in their present form. His Majesty’s (HM) Government should formulate a plan to transform them gradually into predominantly European institutions which conduct defence planning and training, and exercise command, control and communications functions for European armed forces capable of operations without (or with very much reduced) American assets. This does not mean forcing the Americans out, nor necessarily changing the nationality of Supreme Allied Command Europe (SACEUR) – so long as American forces remain in Europe, at whatever level, they should remain involved. But their role should become increasingly advisory and supportive.
Secondly, Britain needs a second means of nuclear delivery, capable of launching nuclear weapons for sub-strategic or tactical missions. With the benefit of hindsight, it was a mistake (one which the French did not make) to phase out the WE177 gravity bomb and rely exclusively on Trident. The UK should immediately reconstitute the WE177 warhead programme, and investigate ways of fitting it to drones or stand-off missiles as well as aircraft. In addition to this, Britain should offer to make it available on a dual key basis (similar to the arrangements it currently has with the US) to the Germans.
Policy Fellow (China Observatory), Council on Geostrategy
In the case of Taiwan, the UK has much to learn from the island which, for decades – and for the foreseeable future – has lived with one eye looking across the strait, and built up multifaceted defence capabilities should its big and increasingly belligerent neighbour decide to attack.
In the realm of cyber warfare, Taiwan has been besieged by Beijing for some time – in 2024, it was the most targeted country in the Asia-Pacific region for cyber attacks. Taiwan has built up a strong cyber capability ecosystem to tackle these attacks, which range from hacking into government systems to conducting pervasive disinformation and misinformation campaigns on social media.
The most effective way for Britain to boost its defence posture is to learn from its allies’ strengths. A senior official at a defence forum in London suggested bilateral UK-Taiwan cyber security training programmes. Britain is no stranger itself to cyber attacks, which are only increasing in number. This is why John Healey, Secretary of State for Defence, stated in the build-up to the publication of the SDR that the UK will increase its cyber attacks on the People’s Republic of China (PRC) and Russia – two countries where many of these attacks prevail.
In the same way that Taiwan faces cyber attacks from the PRC, and the UK from Russia, both islands suspect the same nations of sabotaging undersea cables near their territories. This is another key area where Britain and Taiwan should work together, as both islands face sub-threshold warfare by Beijing and Moscow, with undersea cable cutting as one element of this.
Programme Director for Security Studies, Centre for Defence Strategies, and Joint Programme Leader, Future of Ukraine Programme, Centre for Geopolitics, University of Cambridge
If Britain aims to lead in innovation and development, deepening its partnership with Ukraine is not just strategic – it’s essential. The scope for cooperation can be significantly expanded through the landmark 100-year agreement with Ukraine and the recent UK-European Union (EU) framework, particularly in defence collaboration.
Ukraine brings to the table unmatched, battle-tested expertise – from real-time engagement with Russian forces and cutting-edge technological innovation to agile public-private defence partnerships, societal resilience and the rapid transformation of institutions under wartime pressures. Britain has acknowledged the critical value of Ukraine’s combat experience, incorporating it as a key reference in shaping the SDR. This recognition marks a pivotal moment to build a truly future-oriented partnership; one which links innovation, deterrence and resilience in the face of a rapidly evolving security environment.
Building on the successful execution of Operation SPIDER’S WEB, the UK has committed to studying this combat experience in depth and integrating its lessons into British military training. This is just one of many contributions Ukraine stands ready to offer – lessons born from the frontline which can reshape modern military thinking.
To realise the ambitious vision of the British Army’s ‘Future Soldier’ strategy, the UK is launching a sweeping programme of institutional reform. Personnel systems, training doctrines, administrative structures and organisational cultures will be retooled to meet the demands of future warfare. For Ukraine, this transformation offers a blueprint for military modernisation, and a powerful reaffirmation that its experience is not only valued, but foundational to shaping NATO’s collective readiness for the challenges ahead.
Professor of International Relations, University of Kent
As the SDR stresses, Britain must deepen cooperation with its allies and partners to bolster its defence posture amid mounting geopolitical uncertainty and reduced American guarantees. One contribution to meeting this challenge should be a push to turn the UK-EU Security and Defence Partnership (SDP) agreement into a platform for practical cooperation which builds a genuine alliance relationship.
As it stands, the SDP is little more than a commitment to regular dialogue and exploratory cooperation. To add real value to European security, it needs to embrace defence industrial cooperation as its defining strategic purpose.
The SDR acknowledges the importance of the EU to European security, but sets a low level of ambition for the relationship in just tasking the Ministry of Defence with implementing the SDP. However, Brussels also needs to move beyond rigid third-country models and create more flexible pathways for British involvement in areas such as the Permanent Structured Cooperation (PESCO) capability projects and the Security Action for Europe (SAFE) defence industrial initiative. As the SDR outlines the UK’s intent to enhance industrial resilience and technological innovation, swift action by the EU to demonstrate its openness to a tailored associate status – with mechanisms for joint procurement and research – is the minimal basis for a meaningful partnership.
A good start would be for the EU to produce its own formal response to the SDR, stressing its aspiration to be Britain’s foremost multilateral ally.
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Sincerely, Prof Whitman, in 2016-2017 you sir used to at least acknowledge (even while downplaying/dismissing) the UK's position of disrupting and spoiling wherever remotely possible EU developments, nowhere moreso than in defence!
Disappointing that exactly like Menon, Drummond, Grant, Niblett and all the "analysts and experts" Professor Whitman has adopted the revisionist script and pretends none of that ever happened..
But just to be absolutely clear, even irrespective of that historical complication, simply adopting the position that "[...]*The EU is being unreasonable by refusing to consider special treatment and privileged access for the UK.*[...]" is totally DELUSIONAL!!!!!!
Britain’s review reflects a shift from alliance as tradition to alliance as capability. But when it comes to actual deterrence, how much weight should we give to shared doctrine and standards versus hard industrial output? In the U.S., we’re watching the defense-industrial base strain under basic delivery timelines. Curious if you think Britain’s partners will tolerate that kind of lag, or if the UK has a chance to set a faster operational pace?