By Luo Xi and Liu Yan

The United Kingdom and France recently conducted their first-ever joint exercise simulating nuclear strikes. Codenamed "Rummy," the drill represents a key move in shifting UK-France nuclear collaboration from paper commitments to practical operations.

The UK and France are the only two nuclear-weapon states in Europe. In response to shifts in the European security situation and rifts in transatlantic relations, the two countries signed the Northwood Declaration in July 2025. For the first time, the declaration explicitly stated that both sides would coordinate their respective independent nuclear deterrent forces, while establishing a UK-France Nuclear Steering Group responsible for coordinating bilateral cooperation in areas such as nuclear deterrence operations.

In December 2025, the UK-France Nuclear Steering Group convened its inaugural meeting in Paris, during which the British side was permitted to observe France's routine "Poker" nuclear strike exercise on-site—the first time France allowed foreign personnel to observe the drill, which was viewed as a prelude to bilateral nuclear collaboration moving toward joint practical operations. This latest joint exercise simulating nuclear strikes serves as a landmark move extending UK-France nuclear collaboration from the observation level to the air operations level.

For France, its core demand is to promote European nuclear autonomy while consolidating its own leading position in Europe. In March this year, French President Emmanuel Macron stated that he had ordered an increase in the number of nuclear warheads in France's arsenal and proposed a "forward deterrence" plan, inviting multiple European countries to participate in cooperation within this framework. Under this concept, France will offer partner nations opportunities to participate in nuclear deterrence exercises and, under specific conditions, may deploy French strategic nuclear forces on the territory of allied states. France, while providing nuclear protection to Europe, seeks to establish its dominant position in the process of establishing European defense autonomy.

For the UK, participating in the exercise serves two purposes: meeting its practical need for coordinated deterrence and accumulating operational experience in the long run. Currently, the UK’s only nuclear deterrence force is the sea-based Trident submarine-launched ballistic missile (SLBM), with absolutely zero independent air-launched nuclear delivery capability. Apart from procuring 12 F-35A fighter jets to undertake missions under NATO's nuclear-sharing framework—and those jets won’t be delivered for a couple of years, the UK has no substantive arrangements to develop an independent air-based nuclear force. Through the recent exercise, the UK can re-familiarize itself with the mission procedures, formation coordination, and logistical support models of air-based nuclear deterrence. Should it regain air-based nuclear capabilities in the future, the practical experience accumulated now will be of significant reference value.

For a long time, the defense of most European countries has relied deeply on the US-led NATO system, particularly the nuclear protection provided by the US. However, changes in the regional security landscape have made Europe more eager to pursue "strategic autonomy." In terms of practical effect, this nuclear collaboration provides Europe with a potential pathway outside NATO's traditional nuclear-sharing mechanism—meaning that once the US breaks its security commitments, European countries have their own options. The exercise reflects Europe's ongoing attempt to reduce its heavy dependence on the US in the field of military security.

However, against the backdrop of a continuously weakening international nuclear arms control regime, the exercise will add new variables to global strategic stability. On February 5 this year, the US-Russia New START treaty expired without the two sides reaching an agreement on an extension or a replacement framework. For the first time in decades, the two major nuclear powers have no legally binding mechanisms or transparent arrangements to restrain them in the use of strategic nuclear forces, leaving the global nuclear arms control regime on the verge of collapse. Meanwhile, this exercise sets a precedent for two independent nuclear-weapon states conducting joint nuclear-strike operations, which may stimulate other countries to follow suit, push nuclear deterrence blocs or cliques, and potentially incur nuclear proliferation risks.

It is also worth noting that the timing of this exercise closely coincides with the US "Global Thunder" strategic nuclear exercise and NATO's "Steadfast Noon" annual nuclear deterrence drill, which is likely to further exacerbate global security risks. The advancement of nuclear collaboration among European countries could also trigger reciprocal countermeasures from relevant nations, compressing the buffer space for crisis management and heighten the risks of strategic miscalculation and conflict.

(The authors are from the Chinese PLA Academy of Military Sciences)