The most significant announcement from the 2025 Hague Summit was the collective agreement by all NATO allies to raise defence spending to 3.5 percent of GDP on core defence by 2035. This represents the largest sustained defence investment since the Cold War and marks a decisive step toward enhancing NATO’s capabilities. Equally important was the 1.5 percent commitment to deterrence by denial, directed not just at conventional capabilities but also at resilience in areas such as information security and critical infrastructure. Both measures combined send a powerful signal of NATO’s determination to deter adversaries. This journey began with the Madrid Summit in 2022, when NATO adopted a new strategic concept, now reinforced by renewed planning disciplines, updated capability targets, and new nuclear measures. This broader strategy also reaffirmed support for Ukraine, which underscored NATO’s strengthened deterrence posture.
The UK’s evolving role in NATO’s deterrence pathway is apparent in its 2025 Strategic Defence Review (SDR). The SDR outlined five priorities, the most striking being the explicit focus on NATO first and European security second, a notable shift from earlier reviews. It also emphasised enhancing nuclear capabilities, updating conventional forces, fostering innovation in defence, applying lessons from the Russia-Ukraine conflict, and taking a whole-of-society approach to resilience. These measures underscore how the UK is building forces integrated into NATO’s design, ensuring alignment across nuclear and conventional deterrence. Nuclear modernisation commitments could include a £15 billion investment in the warhead programme, building SSN/A-class submarines, acquiring twelve F-35A aircraft, or initiating early work on long-term deterrence. The UK also declared its intention to join NATO’s nuclear sharing mission, signalling readiness to shape and participate in that mission with full political control.
Equally, the Northwood Declaration indicates France’s growing commitment to shaping European resilience through Franco-British cooperation on nuclear deterrence. The declaration introduced stronger language about collective responses to extreme threats and marks France’s first formalised nuclear weapons cooperation agreement with another state, seeming to build on (or emerge as an extension of) the Lancaster House 2.0 defence and security cooperation commitments made between the two countries.
The ongoing war in Ukraine clearly has broader implications for European security architecture. The critical question is not only what happens on the frontlines but how the conflict concludes and reshapes Europe’s security environment. Russia’s ability to reconstitute its forces, possibly with Chinese support, and how NATO should guard against divisions that Russia could exploit, are all questions that need resolving for effective forward movement. This leads to a consideration of collective burden-sharing, strengthening Europe’s industrial base, and adjusting to the U.S. reorienting more heavily toward deterring China. The rise of China is another pressing issue for NATO, particularly in the context of its expanding nuclear arsenal and growing global assertiveness. At the upcoming NPT Review Conference, NATO will need unity to counter disinformation and pressure from both Russia and China.
Finally, NATO must modernise its nuclear sharing arrangements, strengthen its planning processes, and raise the “nuclear IQ” of decision-makers. Flexible, adaptive planning across multiple scenarios is essential for credible deterrence, as is the integration of nuclear and conventional tools. Exercises, capability development, and strategic communication are particularly critical components of this effort.
Overall, while the Hague Summit was a positive milestone, the real test lies ahead: sustaining progress in doctrine, planning, and modernisation to ensure NATO can deter effectively in an increasingly unstable world.