Reassessing Europe’s security strategy – UK in a changing Europe

Zeno Leoni, Benjamin Jones, Sarah Tzinieris, Bence Nemeth, Michele Groppi, and Zoha Naser summarise their recent report* on European security. They offer four recommendations on how to increase European resilience and defence capabilities in light of geopolitical crises and the unreliability of the US as an ally. 

For decades, European security has rested on a simple assumption: that the United States would ultimately step in to defend the continent. Today that assumption is becoming harder to sustain. Developments in Washington, combined with wider shifts in global politics, mean that European governments increasingly need to prepare for a future in which American support may be limited, conditional, or slow. This requires European countries to increase resilience to achieve strategic autonomy. This remains challenging in the short term.

Calls in Washington for Europeans to shoulder more of the defence burden are not new. Successive US administrations have said this for years – in 2011 Secretary of Defence Robert Gates referred to NATO as a two-tiered alliance, one providing ‘soft’ capabilities and one ‘hard’ capabilities. But the tone and method have changed.

The Trump administration relies on pressure in its dealings with allies. Even if this approach is intended as a negotiating strategy – seeking concessions through cycles of escalation and de-escalation rather than a disruption tout court of NATO – it generates uncertainty among allies. At the same time, US strategic documents continue to underline the importance of alliances, and Congress has introduced legal constraints that would make a formal withdrawal from NATO difficult. These factors suggest that influential pro-alliance forces remain alive within the broader American political system.

Still, assuming that the current period of uncertainty will simply pass once the Trump presidency ends would be risky. Debates in the United States about overseas commitments run deeper than any single administration. While US grand strategy increasingly emphasises projecting military power and influence from the seas, with limited interventions – a foundational element of many American strategies since the end of the Second World War – this administration is more strongly influenced by domestic political developments than its predecessors.

In response to the changed geopolitical environment, defence spending across the continent is rising, and several governments have announced major rearmament plans. But spending more money may not by itself solve the underlying problem. Many of the capabilities required for modern military operations – from intelligence and surveillance to space assets and advanced command systems – remain heavily dependent on the United States. These capabilities are expensive and complex, taking time to develop. Europe’s reliance on American support cannot be eliminated quickly.

Institutional fragmentation also complicates the picture. European defence efforts operate through multiple frameworks, including NATO and the EU, while national procurement systems remain largely separate. Greater coordination is clearly needed, but deeper cooperation can also slow decision-making and complicate procurement. Debates about European “strategic autonomy” have emerged partly in response to these challenges. Yet the concept itself remains politically sensitive and somewhat ambiguous. For some, it appears to suggest distancing Europe from the United States or weakening NATO. In reality, the issue is more practical than ideological. In the near future, the goal is not to replace NATO or to detach Europe from the transatlantic alliance. Rather, it is to ensure that European countries have enough capability to act with limited US support.

In near term, four recommendations should be considered.

The first step is to move away from a “D-Day mentality” and recognise that long-standing assumptions about automatic US intervention are no longer sufficient for planning. However, while strategic autonomy remains controversial, framing efforts around resilience rather than strategic autonomy may prove politically more productive and less sensitive. Building resilience means identifying capability gaps that could emerge if US support were limited and gradually working to fill them, while maintaining transatlantic ties. Diversifying partnerships beyond the Euro-Atlantic space will also become increasingly important, including deeper cooperation with countries such as Japan, Australia, and India.

Operationally, European security should adopt a strategy of flexibility to have more options. NATO will remain the central framework for collective defence, but practical initiatives will increasingly emerge through smaller coalitions capable of acting quickly when necessary. Coalitions of the willing of various geometries – including EU+ frameworks that allow non-EU members to participate or exclude some EU members– are likely to allow Europeans to react to Trump’s pressure. These arrangements could remain anchored to NATO standards while preserving the flexibility needed to respond to fast-moving crises. In other words, multilateral institutions remain essential, but smaller coalitions of countries are often better placed to move quickly.

In procurement, Europe should prioritise the ability to integrate quickly when required. Investments should focus on speed, scale and usability rather than technological sophistication alone, with greater emphasis on training, standardisation and interoperability. Defence systems should also be designed with future cooperation in mind, allowing integration when needed rather than treating it as an immediate objective. This will also require clearer signals from politics to the defence industry. Governments need to provide more credible long-term commitments if companies are to expand production capacity and invest in new technologies; but also intervene more profoundly to keep energy costs low and support manufacturing. Without addressing the energy–industry nexus, efforts to expand manufacturing and defence output will remain structurally constrained.

While strategic autonomy remains a longer-term ambition, the immediate goal should be to strengthen European resilience to buy Europe time while expanding its strategic options.

By Dr Zeno Leoni, Lecturer, Defence Studies Department, King’s College London at the Joint Services Command and Staff College of the UK; Dr Bence Nemeth, Senior Lecturer, Defence Studies Department, King’s College London at the Joint Services Command and Staff College of the UK; Dr Benjamin Jones, Teaching Fellow, Department of European and International Studies, King’s College London; Dr Sarah Tzinieris, Lecturer, Defence Studies Department, King’s College London at the Joint Services Command and Staff College of the UK; Dr Zoha Naser, PhD Candidate, Department of War Studies, King’s College London; and Dr Michele Groppi, Senior Lecturer, Defence Studies Department, King’s College London at the Joint Services Command and Staff College of the UK.

*This commentary summarises findings from a wider report produced at King’s College London. The report consolidates recent research and insights from a confidential Track 1.5 dialogue held at King’s College London in early January. The research was supported by the New Government Fund of the Economic and Social Research Council (ESRC), administered by King’s College London.

Contact: Dr Zeno Leoni – [email protected]