In association with Lawrence Livermore National Laboratory (LLNL), Sandia National Laboratories, Ministry of Defence, and Swedish Defence Research Agency (FOI)
Executive Summary
This conference examined three key questions:
- What impact have recent developments in U.S. and Russian policy had on extended deterrence and assurance in the transatlantic context?
- What alternative futures should be considered?
- What European deterrence architecture best serves the interests of the United States and its NATO allies? What steps are needed?
Recent developments in U.S. and Russian policy have significantly affected the credibility and perception of extended deterrence in Europe. On the U.S. side, deterrence strategy has shifted from a single-theatre focus to recognition of a “two-peer competitor” environment, where the U.S. and its allies might need to deter Russia and China concurrently. Nuclear modernisation programmes, though well underway, began before this shift and may no longer match today’s requirements. Washington has also emphasised the need for greater burden-sharing, both in NATO and in Asia, while advances in cyber and space capabilities could complicate allied integration. Russia, meanwhile, has used nuclear coercion as a central tool in its war against Ukraine, relying on deterrence to limit direct NATO involvement. Moscow continues to frame any confrontation as potentially escalating to nuclear war, while reconstituting its forces for a long war of attrition. These dynamics have reinforced the centrality of U.S. nuclear assurances while underscoring vulnerabilities in Europe’s conventional and industrial bases.
Conference participants identified several possible futures for transatlantic deterrence. One option is to maintain robust conventional and nuclear forces to deter both Russia and China simultaneously, though this is costly and politically demanding. Another path could see greater reliance on nuclear weapons to compensate for conventional shortfalls, especially if China draws the U.S. into a major conflict. A third scenario envisions sustaining alliance commitments but reprioritising risk acceptance, with uneven coverage across regions. The most concerning future, however, is a full U.S. pivot to Asia, leaving Europe to assume far greater responsibility. This outcome would likely unsettle NATO cohesion, potentially encourage “friendly proliferation” in Europe, and embolden Russia to exploit perceived gaps. The uncertain impact of new missile defence concepts, such as a prospective “Golden Dome,” further complicates these futures, as such systems could deter adversaries or provoke destabilising pre-emptive actions.
Action points
The most viable European deterrence architecture is likely to be one that strengthens transatlantic integration while deepening European contributions. This means:
- Modernising NATO’s nuclear sharing arrangements
- Raising the “nuclear IQ” of political leaders
- Ensuring flexible planning across both nuclear and conventional domains. The Northwood Declaration (signalling unprecedented Franco-British coordination) is an important step, but one that cannot fully replace U.S. extended deterrence.
To achieve these goals, Europe must therefore pursue:
- Scalable conventional forces
- Modest enhancements in non-strategic nuclear capabilities
- Greater contributions from non-nuclear allies in intelligence, hosting, and resilience
At the strategic level, NATO must:
- Sustain unity in facing Russia.
- Adapt planning to the U.S.’s two-peer problem.
- Invest in capabilities that provide credible deterrence across multiple scenarios.
Only by combining U.S. leadership with a stronger European backbone can extended deterrence and assurance remain credible in a more unstable world.