Nancy and the politics of deterrence: reading the French nuclear offer to Poland

The Treaty of Nancy was signed on May 9th 2025, on Europe Day, by Donald Tusk and Emmanuel Macron in the Lorraine city where Stanisław Leszczyński, the deposed Polish king turned French son-in-law, lived out his exile. Undoubtedly, the ceremony was shrouded in the symbolism of intertwined history. The document replaced the outdated 1991 friendship agreement (and other subsequent partnerships) and joined the small set of first-tier bilateral pacts France maintains with Germany, Italy and Spain – the first such pact, in this case, with a country that does not share a border. Its security clause commits each side to assistance in the event of armed aggression. In turn, the Polish-French Day of Friendship, fixed by the treaty for April 20th, marks the date Maria Skłodowska-Curie was interred in the Panthéon in 1995.

 

Ratification followed through the autumn and winter, and the treaty entered into force on January 22nd 2026. Six weeks later, on March 2nd, Macron travelled to the Île Longue submarine base near Brest and, with the SSBN Le Téméraire behind him, announced what he called “dissuasion avancée” or forward deterrence. Paris would expand its nuclear arsenal for the first time since 1992, cease publishing total stockpile figures, allow the temporary forward-basing of nuclear-capable aircraft on allied territory, and open structured cooperation on deterrence with eight European partners: the United Kingdom, Germany, Poland, the Netherlands, Belgium, Greece, Sweden and Denmark. Norway joined as the ninth partner in late May 2026. Final decision authority would remain, Macron emphasized, with the French president alone. 

Seven weeks later, the first Polish-French Intergovernmental Summit was convened in Gdańsk. Tusk and Macron told reporters that the two governments would now move toward joint exercises, including elements of nuclear deterrence. That last element, the one Polish media seized on most enthusiastically, is also the one resting on the most fragile foundations. 

 

Dissuasion avancée: cooperation, not coverage

 

What Macron announced at Brest is precisely what its French name suggests: dissuasion avancée, a forward extension of deterrent posture rather than a transfer of deterrent commitment. France will permit the temporary forward-basing of nuclear-capable aircraft on allied territory, expand the structured dialogue on doctrine to eight European partners, and invite participation in exercises that simulate strategic missions. What it will not do, and what Macron took care to underline at Île Longue, is share decision authority. There is no co-decision mechanism, no permanent French nuclear presence on allied soil, and no equivalent of NATO nuclear sharing under which American B61 weapons are stationed on the territory of five European states with dual-key consent and locally based delivery aircraft. The offer sits, deliberately, in a category of its own: a tighter commitment than the implicit Article 5 nuclear umbrella that the United States extends to all NATO members, but well short of the formal sharing arrangement that Belgium, Germany, Italy, the Netherlands and Turkey maintain with Washington. Poland sits in neither of those categories today, and Macron's offer does not aim to resemble either set up.

 

The umbrella imagery that dominated Polish reporting after Gdańsk overstates what Brest actually contains. Measured against either nuclear sharing or an Article 5 commitment, what Paris is offering is structured cooperation: meaningful, but in a category that does not amount to nuclear deterrence in the strict sense. France inaugurated its Nuclear Steering Group with Sweden in Paris on April 23rd 2026, three days after the Gdańsk summit, using the same template established with Berlin and London. Stockholm, a non-nuclear state and a NATO member only since March 2024, now sits in an institutional category Warsaw does not. The Gdańsk joint declaration signals the intention to establish a high-level bilateral strategic dialogue on deterrence covering both conventional and nuclear dimensions. However, the form of this dialogue has not yet been specified.

 

 

Domestic fault lines

 

For the Nancy framework to acquire genuine strategic weight, Polish commitment must hold across changes of government. At present, that condition is not fully met. Nawrocki and his Bureau of International Policy have argued publicly that Poland should prioritize inclusion in the American Nuclear Sharing programme, and have questioned whether the French arsenal is large enough to provide a credible umbrella. Tusk's government, while pursuing the French track, has been careful to frame it as an addition rather than an alternative: Warsaw is not replacing the American umbrella with a French one, but adding a layer beneath it. The choreography of Gdańsk reflected the same divide. The president was absent, the venue chosen outside Warsaw, and afterwards the two camps gave contradictory accounts of why, making the visit the latest episode in a long-running domestic power struggle. The constitutional reading is unambiguous: foreign policy is the prerogative of the government, not the president. Paris, in line with that reading, has built the partnership with the government, not with the Polish state in its institutional fullness. The choice has the merit of pace. However, it carries a corresponding risk that a structure built with one side of a domestic divide is more vulnerable should that side lose an election.

 

The mirror image of this problem can be seen in Paris. The treaty was signed by a French president whose mandate ends in 2027. Marine Le Pen, leading the National Rally for over a decade, was barred from running in March 2025 following an embezzlement conviction. Her appeal is expected on July 7th 2026. In her place, Jordan Bardella has emerged as the likely RN candidate and, since autumn 2025, has been the consistent leader in first-round polling at around 35 per cent. Le Pen has stated that the French deterrent should continue to only protect the country by itself. Bardella's stance seems more nuanced: he accepts that French vital interests have a European dimension, but has set out three red lines on the nuclear question (no sharing, no co-financing, no co-decision on the button) of which only the third aligns with what Macron stated at Brest. The other two are less clearly delineated, and could be applied narrowly or used to constrain the kind of structural deepening on which bilateral cooperation depends.

 

Domestic concerns will likely dominate the 2027 campaign, but should foreign policy intrude, it will do so through Russia and European defence. The candidates' positions will then track the mood in France rather than the calculations of allies. Macron, for his part, appears to be moving deliberately to entrench arrangements his successor would find difficult to reverse. Whether path dependencies of integration would constrain a Bardella presidency in practice is contested. What is not contested is that the Nancy Treaty was negotiated by two leaders, both of whom face uncertain political horizons.

Beyond the declarations

 

If the offer has limits, what underpins it is not only paper. The clearest concrete demonstration of this came after Russian drones violated Polish airspace on the night of September 9th and 10th 2025. The next day, with Poland having invoked Article 4 of the North Atlantic Treaty, Macron announced the deployment of three Rafale aircraft to reinforce the protection of Polish territory and NATO's Eastern Flank, coordinating the move with the Alliance and with British Prime Minister Keir Starmer. The aircraft arrived under the new NATO Operation Eastern Sentry. The deployment was reactive and limited, operating below the threshold of open conflict, but it was the first concrete instance in which the political logic that Nancy would later codify translated into French deployed assets in Polish skies. The category Paris uses for deeper engagement with non-nuclear partners – “dialogue de dissuasion” – has its own operational content: structured exchange on doctrine, joint exercises, and, in conditions of genuine threat, the deployment of French Rafale aircraft, themselves capable of carrying nuclear weapons, in allied airspace as a signal of resolve. In addition, according to Defence24, talks are under way to bring Poland in as an observer to Operation Poker, the quarterly nuclear strike exercise of the Forces Aériennes Stratégiques – a status only British representatives currently hold.

 

Beyond the deterrence dimension, the partnership is acquiring an industrial weight that may matter more in the medium term than any single declaration. In artillery, Eurenco, the French explosives and propellants manufacturer, is investing approximately 250 million euros in a joint venture with Polska Grupa Zbrojeniowa to build a propellant and modular charge facility in Pionki. The project contributes to the wider European effort to close ammunition shortages, with production expected to begin in 2028. In the air, Poland is advancing plans to acquire two Airbus A330 MRTT aircraft, with an option for two more, and deliveries expected from 2029 onwards (though this is a pan-European Airbus programme rather than a strictly French one). In space, the two high-resolution Pléiades Neo reconnaissance satellites Poland contracted from Airbus Defence and Space in 2022 are now being integrated in Toulouse for launch by 2027. The first cohort of Polish operators completed their training there in late 2025. The civil nuclear track is moving in parallel from declaration toward contract: the Cooperation Plan signed alongside Nancy in May 2025, the selection of the French Arabelle turbine for Poland's first nuclear plant, and EDF's competitive dialogue for the second-site project all sit downstream of the same logic. Gdańsk itself added two further tangible commitments. The first was an industrial cooperation agreement signed at the summit by Airbus Defence and Space, Thales Alenia Space and the Polish RADMOR to develop a geostationary military communications satellite for the Polish Ministry of National Defence. This was agreed as part of the EU's Readiness 2030 framework in the presence of Polish Defence Minister Władysław Kosiniak-Kamysz and French Minister of the Armed Forces Catherine Vautrin. The second agreement was the joint declaration committing Poland to its first participation in the French ORION exercise in 2026, and France to renewed participation in the Polish DRAGON exercise in 2027.

 

What these arrangements buy is not a substitute for institutional architecture but partial insulation against the political calendar. Industrial commitments, signed contracts, satellites already in integration, ammunition lines under construction – these are agreements that survive elections more reliably than political pledges of intent. They do not survive them perfectly: a sufficiently determined successor in either capital can slow procurement, defer next steps, or quietly let cooperation drift. But the cost of doing so rises with the volume of material commitment already in place. To the extent that the year between Nancy's entry into force and France's next presidential election is used to multiply such commitments, the partnership acquires a kind of durability that declarations alone cannot generate: weight, and the habit of cooperation that weight produces.

 

Racing the calendar

 

Russia is the immediate reason Nancy was negotiated, but not the only one: it answers both a threat from the east and a growing uncertainty to the west, as Washington's commitment to European defence looks less dependable than it once did. Whether what is being built actually deters still depends, first of all, on how Moscow reads it. For Europe, the central fact is that each layer of European defence cooperation raises the costs of aggression on the Eastern Flank. The drone incursions of September 2025 were a probe that aimed to test this situation. The response of three Rafales over Polish skies was an answer Moscow registered. Yet the Kremlin watches the political calendar in Paris and Warsaw as closely as the terms of the agreements. The 2027 elections offer Russia an opportunity it has used before: to push outcomes towards candidates whose victory would weaken European defence ties, narrow support for Ukraine, and slow the institutional deepening it would prefer to interrupt. Paradoxically, each such effort, whether against airspace or against the ballot, has so far accelerated the very dynamic it was meant to weaken.

 

None of the commitments accumulating around Nancy individually amounts to a strategic alliance, but together they form a structure that, if developed further, becomes increasingly difficult to dismantle. What the next twelve months will decide is not whether France will extend its deterrent over Poland, which it has signalled it will not, but how much of this material becomes contractually binding, operationally embedded, and institutionally anchored before the political calendar intervenes. While the two governments' interests align, the window must be used to its limit. Every contract signed, every exercise embedded, and every commitment locked in is a unit of deterrence on the Eastern Flank that survives whoever takes office in 2027.

 

Nicole Czaplinska is an independent journalist with a particular interest in armed conflicts, NATO, and defence policies. Her professional experience includes policy analysis, political affairs at the Polish Embassy in Paris, and reporting from Beirut.