The Nancy treaty: friendship without commitment?

Introduction

On May 9, 2025, French President Emmanuel Macron and Polish Prime Minister Donald Tusk signed a bilateral treaty on strengthening cooperation and friendship in the French city of Nancy.1 The agreement, intended to replace the previous Franco-­Polish treaty of 1991, continues the policy of rapprochement between the two countries that began after 2022. The document, including its military provisions, has attracted particular attention not only in the context of the ongoing conflict in Ukraine—in which Paris and Warsaw are providing military and political support to Kyiv—but also in light of statements by French and Polish officials emphasising the treaty’s key importance for bilateral relations. The choice of Nancy as the signing venue carries symbolic significance, evoking Polish—French relations of the eighteenth century and underscoring the treaty’s special status. It was in Nancy in 1736 where Polish King Stanisław Leszczyński, father-in-law of French monarch Louis XV, settled as Duke of Lorraine after fleeing the Polish-­Lithuanian Commonwealth to escape the advance of Russian imperial troops under the command of General von Minich.

The choice of 9 May is likewise not coincidental. On the one hand, the date marks Europe Day, commemorating the Schuman Declaration of 1950 and the launch of European integration 75 years ago. On the other hand, it may be interpreted as an unambiguous political signal to Russia, where the 80th anniversary of the Victory over nazism in the Second World War was commemorated on the same day.

Although symbolism remains an integral part of political decor, it is more important to examine the content of the new treaty and assess its significance, which is the main aim of the article. The Polish government, followed by the Polish media, called the agreement in Nancy a “turning point”, presenting it as a major diplomatic success and a significant boost to Poland’s national security.2 In France, politicians and the press regard the treaty as an important step towards strengthening the European Union.3

Due to the novelty of the subject, analytical work on the topic has so far been limited to expert commentary by political scientists from Poland, France, and Russia. Their articles describe the state of Franco-­Polish relations [1; 2], the current European context and the dynamics of France’s conclusion of similar agreements with EU partners [3], the main provisions of the agreement and opportunities for bilateral cooperation. The authors emphasize the symbolic significance of the agreement — from “joint resistance to the Russian threat” to “an attempt to rewrite the history of Franco-­Polish relations” based on trust and “strategic brotherhood” [4], noting that it is more about a desired framework for cooperation, which has yet to be filled with content, than about any real guarantees [1; 5]. Although these comments are useful in allowing the reader to see the specifics of contemporary Polish-­French relations, as well as the ambitions and positions of the two parties in concluding the agreement, they do not, of course, exhaust the matter.

To assess the substantive significance of the treaty, it should be situated within the temporal and spatial contexts of Franco—Polish relations, an approach that is methodologically consistent with the concrete-­historical perspective. This requires an examination of the main stages of bilateral relations between 1991 and 2022 and an evaluation of their outcomes, an analysis of the key provisions of the Treaty of Nancy from the standpoint of the national interests of France and Poland, and a determination of the treaty’s place and significance among similar agreements concluded by France with other major EU and NATO member states. This comparative positioning constitutes the principal novelty in the present study.

The authors address these tasks through the application of the historical-­systematic method, which enables an analysis of the dynamics of Franco—Polish relations in light of both internal and external factors, as well as through comparative analysis, which allows the Treaty of Nancy to be systematically compared with other agreements concluded by France in recent years.

The dynamics of Polish-­French relations in 1991—2022

After the end of the Cold War and the bipolar world order, and following the demise of the USSR, Franco–Polish relations evolved in a non-linear and uneven manner, marked by periods of both rapprochement and setback. The dynamics of political and economic contacts were influenced by both objective factors — the external (European and international) environment — and subjective factors — the political goals of the leaders of the two countries and their ideological priorities.

The political elites who came to power in Poland as a result of the 1989 Round Table talks sought to establish the friendliest relations possible with Paris [6]. Building on shared historical traditions, Poland and France quickly moved towards closer relations, signing the Treaty of Friendship and Cooperation in 1991 and becoming partners within the Weimar Triangle, an initiative designed to strengthen cooperation among Poland, France, and Germany and to facilitate the integration of post-communist countries of Eastern Europe [7; 8]. In the Treaty, both sides declared their desire to jointly build a democratic and united Europe, and France also pledged to support Poland’s European integration aspirations. The countries also agreed to work together for peace and security in Europe, including within the CSCE/OSCE, and developed a mechanism for regular political dialogue and urgent bilateral consultations in the event of threats to the peace and security of the two countries.4

However, after 1991, the dialogue between Warsaw and Paris developed unevenly. For example, in the early 2000s, Polish-­French relations were far from friendly, which was the result of significant differences in the views of the leaders of the two countries on the role of Europe, the US and Poland itself in the world [9]. In the 1990s, Presidents François Mitterrand and Jacques Chirac were cautious about Poland’s accession to NATO and the EU, considering Polish foreign policy to be too pro-­American and Atlanticist, especially since this led to financial and image losses for Paris as, for example, in the case of Poland’s purchase of American F-16s instead of French Mirage-2000-5 fighters at the end of 2002.5 It may seem like a technical incident, but it had a significant impact on the mood of the French ruling circles, who began to accuse Poland of ingratitude in response to French support for its accession to the EU. An even more negative impact on Polish-­French relations was caused by the diametrically opposed positions of the countries on the issue of the American invasion of Iraq [10]. Poland’s unconditional solidarity with the US and the participation of the Polish armed forces in the intervention convinced Paris that Warsaw was more interested in developing a Polish-­American military-­political partnership and strengthening its position at the transatlantic forums than in the processes of European integration. The Polish side reacted strongly to Jacques Chirac’s sharp rebuke during the Iraq crisis, in which he stated that Poland and other Eastern European countries had “missed an opportunity to remain silent” [11, s. 41]. Several months later, in October 2003, the Polish Ministry of Defense made statements, later refuted, that French Roland missiles, which France allegedly continued to supply to Saddam Hussein’s government in violation of the UN embargo, had been found in Iraq. These statements damaged Poland’s image in France completely. The rise to power in Poland between 2005 and 2007 of the Eurosceptic national-­conservative government led by the Kaczyński brothers and their Law and Justice party (hereinafter PiS) marked a turning point in bilateral relations, as Warsaw ceased to regard Paris as a priority partner within the EU. Concurrently, political discourse in France increasingly framed Poland as a “Trojan horse of the United States in Europe” [12, s. 148]. In an interview published in the Lorraine newspaper L’Est Républicain, former French ambassador to Poland Pierre Buhler pointedly regretted that after 1991 the Poles quickly forgot the “numerous gestures of solidarity from the French” and began to believe that only “the US protected them from the Soviet Union, and that joining NATO was the only and final guarantee of the country’s security.“.6

Some normalisation of Polish-­French relations began only in 2008, after the formation of a pro-­European government in Poland under Prime Minister Donald Tusk. On the French side, the return of Paris to the Alliance’s military structures (April 2009), announced by Nicolas Sarkozy at the end of 2007, also contributed to some warming of relations. At the same time, on Sarkozy’s initiative, Poland was invited to participate in regular meetings of ministers of the largest EU countries (G-5). In Warsaw, this gesture was seen as a long-awaited confirmation of Poland’s important status in the EU and Paris’s willingness to make Poland part of the “engine of European integration” [11, s. 43]. On May 28, 2008, Donald Tusk and Nicolas Sarkozy announced their desire to form a strategic partnership between the countries by signing a five-year cooperation program7, and Poland became interested in the French concept of “Europe de la defence”. Radosław Sikorski, then head of the Polish Ministry of Foreign Affairs, confirmed the country’s readiness to become more actively involved in EU defence projects, primarily within the framework of the European Security and Defence Policy. The result and symbol of bilateral rapprochement was the Declaration on European Security and Defence signed by Nikolas Sarkozy and Donald Tusk on November 5, 2009.8 The document provided for the strengthening of bilateral cooperation between Poland and France in the development of the European Security and Defence Policy as a complementary pillar to NATO, the expansion of bilateral military and technical cooperation, and joint action in addressing international and European security challenges [13, s. 141—143].

The 2009 Paris Declaration became a symbol of the rapprochement between Poland and France in the dialogue on European security issues and led to the intensification of bilateral cooperation within the framework of both the Weimar Triangle [14] and the so-called “Club of Five” (“Weimar Triangle” + Spain and Italy), which lasted until 2015. In June 2014, France temporarily deployed its fighter jets near Malbork for the first time to conduct air patrols for the NATO mission in the Baltic region. France used this period to promote its military-­industrial complex and energy sector products in Poland. Among French proposals, there were joint projects in the defence industry as well as proposals to build Poland’s first nuclear power plant. The parties reached certain agreements in April 2015, signing a preliminary agreement worth € 3 billion for Poland to purchase fifty H225 Caracal multi-­purpose helicopters from the Franco-­German-­British consortium Airbus [15, p. 264].

However, the return to power in 2015 of Jarosław Kaczyński’s Law and Justice (PiS) party, after its victories in the parliamentary and presidential elections and its openly critical stance towards Brussels and the principal states of the European Union, was followed by a marked deterioration in Warsaw’s relations with Paris. In October 2016, the Polish government cancelled the tender for the purchase of Caracal helicopters, preferring the American UH-60 Black Hawk. That was a blow to France, already struggling to compete with the US in the European arms market. Such renunciation of agreements, coupled with harsh statements by Polish representatives towards French politicians and society, could hardly be interpreted as anything other than Poland’s lack of interest in developing military-­industrial cooperation with major European players [16, p. 46]. As the French and German defence ministers
Jean-­Yves Le Drian and Ursula von der Leyen noted in a letter to their Polish counterpart, Antoni Macierewicz, that Warsaw’s behaviour towards Airbus called into question Poland’s interest not only in trilateral cooperation, but also in European cooperation.9 The uncompromising and explicit focus on military-­political cooperation with the US first led to the cancellation of French President François Hollande’s visit to Warsaw in October 2016, and then to a full-scale freezing of Polish-­French relations [17]. Throughout 2015—2021, mutual resentment was exacerbated by Warsaw’s protracted conflict with Brussels, Paris and Berlin over issues of respect for the rule of law and democratic norms in Poland. The countries took opposing positions on almost the entire range of issues on the European agenda — from migration policy to global warming [1]. Attitudes toward Russia’s foreign policy, including issues of NATO and EU expansion to the east and the assessment of conflicts in the post-­Soviet area, remained a constant source of irritation. In discussions on these issues, Poland’s tough anti-­Russian stance was at odds with France’s more moderate position, in the Ukrainian crisis as well (2014—2022) [18, pp. 177—178].

France’s involuntary revival of interest in the states at the eastern flank of the EU after Brexit [19, pp. 10—11] and the official visit of French President Emmanuel Macron to Warsaw in February 2020, although caused poorly concealed satisfaction in Poland with the “long-awaited recognition” of its role in the EU10, did not lead to any noticeable breakthroughs in bilateral relations.

Circumstances of the signing and main provisions of the treaty

The rapprochement between the two countries began only in the light of the events of 2022—2025, which forced Paris and Warsaw to reconsider the status of their relations. After Russia launched a special military operation in February 2022, Poland welcomed France’s tougher stance on Russia. It should be noted that while in 2022 Emmanuel Macron attempted to mediate between the EU/NATO states and Russia, by early 2023, Paris’s shift towards Atlanticism had become apparent. The French leader’s flowery apologies in Bratislava on June 1, 2023, for the West’s alleged ‘failure’ to hear on time coming from Eastern Europe warnings about Russia were perceived in Poland as a final acknowledgement of the correctness of its tough anti-­Russian course over the past 15 years.11 Warsaw’s expectations that its strategically important position on the eastern flank of the EU and NATO, its role as the main military and technical hub for aid to Kyiv, and its ambitious plans to increase the size and modernise its army would lead to recognition of its role in the EU have been partially justified. For French politicians and analysts, Poland emerged as the de facto leading actor in efforts to contain Russia in Eastern Europe during the period 2022—2024 [20; 21].

The latest change of government in Warsaw has significantly contributed to the intensification of Franco-­Polish dialogue [2]. The return to power of the pro-­European coalition led by Donald Tusk, following the parliamentary elections in the autumn of 2023, which was enthusiastically welcomed in Western Europe, led to a rapprochement between the countries on a number of issues.12 Emmanuel Macron’s meetings with Donald Tusk on February 12, 2024, in Paris and on December 12 of the same year in Warsaw signalled a warming of relations and the preparation of a new bilateral agreement [22]. Drawing attention to Tusk’s visit to France on February 12, Emmanuel Macron posted a message in Polish on social network X:* “I am delighted to welcome you, dear @DonaldTusk. This is your first visit since taking office as Prime Minister, marking a new chapter in our relations with Poland. Let us continue to work together for the security and independence of Europe!” .13 Finally, the crisis in transatlantic relations that emerged following the return of Donald Trump’s administration to power in the United States in January 2025, together with growing uncertainty surrounding American security guarantees, further encouraged Paris and Warsaw to view each other as key allies in strengthening European security [23, p. 140].

The Treaty on Strengthening Cooperation and Friendship, signed on May 9, 2025, officially replaced the Treaty on Friendship and Solidarity, signed in Paris on April 9, 1991. Due to the continuity of the documents, the structure of both treaties is very similar and covers cooperation in the fields of foreign policy and European integration, security and defence, economy, science and culture, environmental protection, migration, youth policy and other areas — each with adjustments for the realities of 1991 and 2025. The Treaty of Nancy replaces earlier declarations from the 2000s on cooperation in strengthening European security, which have become obsolete over the past decade due to profound changes in Europe’s security environment. The key provisions of the treaty have caused the greatest resonance in the countries and are capable of influencing the further development of bilateral relations between Warsaw and Paris.

First and foremost, the treaty provides for a significant deepening of bilateral political and military cooperation (Articles 1 and 4). Annual bilateral summit meetings between the French president and the Polish prime minister, with the participation of members of the governments, are established as a new basic form of political dialogue. The treaty also provides for annual consultations at the level of foreign ministers, defence ministers, chiefs of general staff and heads of services responsible for supplying the armed forces with weaponry. The treaty also broadly outlines the possibility of strengthening cooperation at the level of the parliaments, civil society and business communities of the two countries.

Although both the Poles and the French present the Nancy Treaty primarily as an agreement on strengthening common security, only one article (Article 4) is devoted to security and defence issues, and it is the central one. The parties attach particular importance to paragraph 2 of Article 4, under which the parties undertook to assist each other in repelling military aggression: “The parties shall provide mutual assistance, including military assistance” — in accordance with Article 51 of the UN Charter, Article 5 of the NATO Treaty and Article 42.7 of the EU Lisbon Treaty. Thus, first, this provision of the treaty does not create any new basis for providing military assistance and does not entail any additional allied obligations beyond those already binding both countries under the above-­mentioned international documents. Secondly, although the parties of the treaty have promised to provide mutual assistance to each other in the event of a military attack, including military means, there is no mention of them committing to assist each other specifically with all available means. Furthermore, this assistance is subject to the frameworks of the UN, the EU and NATO. It does not oblige France to act beyond the limits of the decisions of these structures. In fact, Paris leaves the decision on the format of military assistance to its own discretion. Moreover, there are no French military contingents in Poland yet [1]. In Poland, however, it is believed that the very signing of the new treaty emphasises the importance of previous allied commitments and thus serves primarily as an element of deterrence against Russia [4].

In Article 4, the parties emphasise the leading role of European values, transatlantic relations, ties between the EU and NATO, “European defence” and Euro­peans’ responsibility for ensuring their own security as strategic priorities. The treaty places a noticeable emphasis on the need to expand the EU’s independent defence capabilities, as well as to strengthen European technological and industrial capabilities in the defence sector. Undoubtedly, at the instigation of Donald Tusk and his pro-­European and liberal government, Poland is “signing up” to the protection of European values (in defiance of its domestic political opponents) and emphasizing the importance of “European defense”, while France, for its part, recognizes the importance of security of Central and Eastern Europe, thereby creating a basis for involvement in ensuring it [1; 5]. Although the text makes it clear that these ambitions are not aimed at replacing NATO, but at developing its European ‘‘backbone’’ in the context of US expectations for greater responsibility on the part of European allies for their own security, a part of the Polish political elite has reacted sharply negatively to them. Behind the wording that “Europe must take greater responsibility for its defence,” “take independent action and deal with immediate and future security threats and challenges” (Article 4, Paragraph 1), the Polish Eurosceptic and national-­conservative opposition saw attempts to promote the idea of creating European armed forces independent from NATO.14

Paragraphs 3—7 of Article 4 spell out several formats designed to bring the armies of the two countries closer together: joint exercises, increased interoperability, simplified transit and deployment of armed forces on each other’s territory, cooperation between military-­industrial complexes and military academies, all of which are intended to create a “common strategic culture”. The leaders of the two countries have already announced participation in joint military exercises and the strengthening of ties in the field of arms procurement and production.15 The same goals are ensured by Paragraph 9 of Article 4 on promoting the principle of European preferences in arms procurement. This creates a legal basis for the development of various military-­industrial programs involving the MICs of both countries. France is likely to use this clause to obtain Polish arms contracts (including submarines and refuelling aircraft). Representatives of the French companies Naval Group and Airbus have already expressed interest in holding consultations with their Polish counterparts on specific projects, but it is not yet clear whether they will meet Poland’s requirements [5]. Warsaw is already implementing one costly “strategic partnership” with the US and is unlikely to agree to new arms purchases in exchange for rather vague security declarations.

The “European preferences” declared in the agreement are still at odds with reality — the US and South Korea remain Warsaw’s most important partners in arms procurement. Poland, for its part, is clearly hoping to gain access to multilateral European defence industry projects, to which it has been virtually denied access until recently. It may be assumed that Donald Tusk’s government plans to use this opportunity to increase the country’s involvement in military-­industrial cooperation within the EU and European Defence Fund (EDF) projects, which have so far remained insignificant.

Given past scandals in military-­technical cooperation between the two countries, implementation of this point still appears difficult, especially after the victory of PiS candidate Karol Nawrocki in the Polish presidential elections in May 2025. An ardent admirer of Donald Trump and an advocate of further strengthening Polish-­American ties in the field of defence cooperation, Nawrocki will obviously seek to block those initiatives of the Tusk government that could harm the interests of the American MIC and business in Poland. France, in turn, is also unlikely to change its policy of blocking the Polish military-­industrial complex’s participation in European projects, including the Franco-­German development of the new-generation MGCS main battle tank.

Finally, the agreement creates a basis for deepening bilateral cooperation in the field of peaceful atomic energy (Article 9), allowing for the construction of nuclear power facilities and nuclear reactors. A cooperation plan on this issue has also been signed. In honour of the joint discovery of radium by Pierre and Marie Curie on April 20, 1902, a Franco-­Polish friendship holiday is established (Article 11). In general, Poland, which is still heavily dependent on coal, is interested in diversifying its energy sources, and France, as a nuclear power, is ready to act as a supplier of relevant technologies, for example, in the construction of an EPR water-­cooled nuclear reactor.16 However, the prospects for Franco-­Polish cooperation in this area are not yet clear. In 2021—2022, Warsaw rejected three proposals from French energy companies participating in a tender for the construction of the first nuclear power plant in the republic in favour of the American Westinghouse company.

At the same time, the issue of French nuclear weapons being deployed on Polish territory, which is of particular concern to Warsaw, is not addressed at all in the agreement. Although Donald Tusk is trying to ‘save face’ by emphasising that this issue remains subject to further discussion with France based on the Nancy Treaty, the French doubt whether the Polish side is willing to take the risk and finance the storage of foreign nuclear arsenal, the decision to use which, if necessary, will be made solely by the French president.17 In Poland, particular attention has been paid to President Macron’s statements that the mutual assistance clause “covers all components” and that France’s vital security interests have a “European dimension” and will be defined with due regard to the interests of its “main partners” [4]. Such vague wording is traditional for France, whose doctrinal documents, based on the interests of nuclear deterrence, deliberately do not specify the boundaries of the territory protected by French nuclear weapons. Therefore, these boundaries implicitly include the territory of both France and its European allies.18

Some Polish experts note that this statement by the French leader clearly confirms the possibility of France using its nuclear weapons to protect Poland’s security interests, while others emphasise that Macron’s statement is “ambiguous in a French manner” and cannot be interpreted undoubtedly this way [4]. Nevertheless, the absence of even a hint of such a possibility in the Nancy Treaty clearly contrasts with the rhetoric about the “coincidence of the vital interests of both countries” in the Anglo-­French Lancaster Treaty of 2010 and the “inseparability of security interests” and “use of all available means for mutual defense” in the Franco-­German Aachen Treaty of 2019 [10; 24].

In other areas of bilateral cooperation, a significant part of the Treaty is devoted to the development of relations in the fields of economics, energy, industry and digital policy. The treaty creates a platform for initiating joint projects, primarily in the field of developing technologies of the future—artificial intelligence, quantum computing, biotechnology, microelectronics, cloud computing and hydrogen technologies (clause 8, article 6).

In the area of global challenges for Europe, the parties have declared their commitment to maintaining the competitiveness and stability of their economies while accelerating reindustrialisation, digital transformation and reducing greenhouse gas emissions (Article 6, paragraph 3). In the context of environmental and climate issues, it is unclear how exactly and how quickly the parties intend to overcome the fundamental differences in their current policies on these issues [25, p. 385]. In particular, Article 7 of the treaty, which envisages the implementation of the EU’s climate program by 2030, directly contradicts both the “anti-green” sentiments of Polish society and the actions of Donald Tusk himself to block certain elements of the EU’s “Green Deal”. Similar questions raise the intention of the two countries, declared in Article 5, to develop cooperation in the field of migration policy, given the significant tightening of Warsaw’s migration policy as part of Poland’s new strategy for 2025—2030 and Donald Tusk’s sharp criticism of the new EU Migration Pact.

Nancy Treaty among its ‘‘cousins’’: a European dimension

Besides the temporal framework of Polish-­French relations, the Treaty of Nancy also fits into the EU spatial framework, continuing the range of agreements concluded by France with other major EU and NATO member states. They are Germany (Aachen Treaty in 201919), Italy (Quirinal Treaty in 202120), Spain (Barcelona Treaty in 202321) and Portugal (Treaty of Porto in 202522). All of these treaties were concluded within a relatively short interval and are characterised by a high degree of structural similarity. Collectively, they cover a wide range of areas of interaction, including bilateral cooperation, European and foreign policy, and matters of defence and security. Their signing, initiated by France, may pursue three goals. First, to update the partnership framework, as more than fifty years have passed since the beginning of European integration, and the new realities that have emerged over this period have substantially reshaped the EU without being adequately reflected in earlier treaties. Second, to stimulate the development of “multi-­speed integration” within the EU [26, p. 34—35], including the emerging of a common strategic culture (a common approach to understand the EU “strategic autonomy”), which is important for Emmanuel Macron, at two levels — administrative (regular consultations between ministers and officials) and public (exchanges, joint trainings etc.). Third — the signing of a range of agreements may indicate Macron’s desire to strengthen the intergovernmental framework for integration [26, p. 41], to avoid the dependence on Eurosceptics if they could rise to power. Moreover, France finds itself at the centre of this ‘‘web’’ that allows Paris to spearhead integration by manoeuvring between Germany and other states representing the South and East of the EU.

All of these agreements are heterogeneous. They differ in the circumstances of their signing, their titles, scopes, formats of interaction, declared priorities of the foreign policy, and their commitments in the areas of defence and security. Each of these treaties possesses its own distinctive profile. In this respect, the Treaty of Nancy is both comparable to and clearly differentiated from its related agreements (see Table 1).

Comparison of five treaties, concluded by France, by key parameters

First of all, let us note the different titles of the agreements, which define their main ideas. The Nancy Treaty for Enhanced Cooperation and Friendship is far from the degree of closeness established by the Aachen Treaty on Cooperation and Integration. It seems to be closer to the Barcelona or Porto Treaties of Friendship and Cooperation. Nevertheless, in terms of the number of articles (19), a parameter reflecting the volume and detail of the subject of regulation, the Nancy Treaty is inferior to almost all given agreements, exceeding only the Quirinal Treaty (12).

As for cooperation formats, the Nancy Treaty introduces some measures familiar to other agreements: they are summit meetings, consultations at the level of foreign ministers and defence ministers (2 + 2 format), and interparliamentary cooperation. But their frequency and degree of convergence do not allow us to say unequivocally that Poland is becoming for France a partner on an equal footing with Germany, Italy and Spain. Thus, Franco-­Polish summit meetings are declared to be held once a year (Clause 2 of Article 1), as are Franco-­Italian and Franco-­Spanish ones, while Franco-­German meetings are to be held at least twice a year. Moreover, the Nancy Treaty (as well as the Treaty of Porto) lacks a symbolic but significant element — the participation of a member of the government of one of the states in a meeting of the Council of Ministers of the other side once per trimester, although this clause is present in the other three treaties. Consultations at the level of foreign ministers are described in the Nancy Treaty merely as “regular,” whereas in Franco—German relations they are held at least once every three months, and in the Franco—Italian framework, on an annual basis. With regard to meetings of defence ministers, the Nancy Treaty, like the Treaty of Porto, does not provide for the establishment of a defence and security council, in contrast to the other three treaties. Nevertheless, it does envisage regular consultations in the 2 + 2 format involving the heads of the foreign and defence ministries. Finally, at the level of interparliamentary cooperation, the Aachen Treaty explicitly envisages the creation of a joint Franco—German Parliamentary Assembly. None of the other four agreements, including the Nancy Treaty, provides for a comparable degree of parliamentary rapprochement.

Each of the five agreements sets out the priorities for cooperation between the parties, which can be divided into three groups: bilateral relations, the development of European integration, and the attitude towards world order and multilateralism. [27, p. 21]. The Nancy treaty does not contain any mention of a single economic area (as in the Aachen Treaty) or of enhancing the monetary union (as in the case of the Quirinal and Barcelona Treaties). Like the Treaty of Porto, it states only the development of a “common market”. Although the Nancy Treaty provides for a bilateral economic forum (unlike the Franco-­Italian and Franco-­Spanish agreements), it shall not be held annually, but just “at least once every two years” (Article 6). However, the Nancy Treaty is the only one of the five agreements that contains a separate article on cooperation in peaceful nuclear development. Anyway, Spain, as well as France, also has nuclear power plants, and the Quirinal treaty could facilitate Franco-­Italian cooperation in constructing a system of small modular nuclear reactors [28, p. 10].

Advocacy of European integration runs through all five agreements, but every treaty has its own nuances. Like its ‘‘cousins’’, the Nancy Treaty declares support for the joint work of EU member states outside the Old World, including the Europe-­Africa partnership. Like the agreements of Quirinal, Barcelona and Porto, the Nancy Treaty highlights the importance of links between the EU and the Mediterranean. Like its Barcelona and Porto ‘‘cousins’’, the Nancy Treaty sets out support for EU enlargement and the development of a “European Political Community”. However, the Treaty of Nancy displays a more pronounced orientation towards Euro-Atlanticism and a stronger tendency towards the securitisation of policy domains. It establishes not only European integration but also transatlantic relations as strategic priorities, aligning it with the Treaties of Quirinal and Porto. Moreover, the Franco-­Polish cooperation is included within the framework of the Weimar Triangle and the Eastern Partnership, and the importance of ties between the EU and the Arctic, Asia, and the Indo-­Pacific region is also emphasised (Clause 4 of Article 2). Although all five treaties declare their support for multilateral governance formats (multilateralism) based on the principles of the UN Charter, the Nancy Treaty does not mention either a rules-­based world order (as it is in the Aachen treaty) or a law-based world order (as it is in the Treaties of Quirinal, Barcelona and Porto), but modestly affirms respect for international law (Clause 1 of Article 3). All these features could be explained by a new context — the development of the Ukrainian conflict in Europe. Thus, the Nancy Treaty directly affirms the increasing threat to European security as a result of Russia’s special military operation in Ukraine, surpassing in this the Barcelona treaty, which contains just a vague reference to the “combination of crises and threats unseen since the Second World War”.

The central element of the five treaties is the parties’ defence commitments, which are all bound by the NATO and EU frameworks. This is a rare case where the Nancy Treaty is closer to the Aachen Treaty than the other three agreements. In the Aachen Treaty, France and Germany promise to assist each other “by all available means, including military ones” (Clause 1 of Article 4). The Nancy Treaty, as shown above, contains a commitment to provide military assistance, but it is less concrete, and the other three agreements do not mention military assistance at all — a feature which seriously weakens the obligations set out in them.

All treaties also contain articles on cooperation between the armies and military-­industrial facilities of the parties: in all texts, this point is linked with the need “to create the common strategic culture and to conduct joint military operations, joint training and military exchanges”,23 and the convergence and cooperation of military-­industrial complexes in the name of a common “European defence”. The Nancy Treaty, like the Quirinal, Barcelona, and Porto agreements, includes provisions facilitating the transit and deployment of troops on each other’s territory, as well as cooperation in space activities. Similar to its Porto counterpart, the Nancy Treaty emphasises enhancing the interoperability of the two countries’ armed forces and conducting joint military exercises. To sum it up, the Nancy Treaty structurally and thematically continues a range of agreements previously signed by France with leading EU states, and, in comparison with the 1991 Treaty, truly raises Franco-­Polish relations to a level close to the Franco-­German, Franco-­Italian and Franco-­Spanish alliances. But in terms of the declared scale of interaction and the degree of closeness between the parties, it is far from the Aachen Treaty in almost all respects and is much closer to the Treaty of Porto than to its Quirinal and Barcelona ‘‘cousins’’. Nevertheless, Warsaw has clearly joined the group of Paris’s key strategic partners. As for the practical impact of the Treaty of Nancy, as with the other comparable agreements, it can only be assessed in a highly provisional manner, given that the treaty has yet to demonstrate its effectiveness in practice. Against the backdrop of similar treaties concluded among other NATO members, such as the Kensington Treaty of 2025 between the United Kingdom and Germany, it can be argued that European powers are increasingly seeking to establish additional strategic ‘‘backstops’’ by creating or reinforcing bilateral cooperation mechanisms. This trend reflects a growing inclination to hedge against uncertainty by reducing reliance on U.S. security guarantees within NATO and, in particular, on the European Union, whose military capabilities remain in the process of development.

Conclusion

Although the Nancy Treaty can hardly be considered an epochal event in European politics, it marks an important milestone. This agreement differs from the Aachen, Quirinal and Barcelona Treaties primarily in that it was concluded by France not with a neighbouring Western European state, but with an Eastern European one. Thus, France, recognising Poland’s growing role as an economic player and security provider not only in Eastern Europe but throughout the Old World, is seeking to enhance their ties in various areas to the level of French relations with Germany, Italy, Spain, and Portugal. This allows Paris and Warsaw to rely on each other in their relations with Berlin, Moscow, and Washington, including when considering the prospects for the development of the Ukrainian conflict.

Can it be argued that the Nancy Treaty enhances Poland’s level of security? While strengthening relations with a European nuclear power possessing significant military and economic capabilities is undoubtedly beneficial for Poland, the principal challenge lies in the effective implementation of the Treaty’s provisions in practice, including cooperation in the defence-­industrial, military, energy, and economic spheres. Despite political statements suggesting that the Treaty should “change the game”, the new elements it introduces do not so much reshape the balance of power in Europe—neither the Franco—German nor the Polish—American alliances are disappearing [29, p. 97]—as create favourable conditions for the further development of cooperation between France and Poland. Indeed, the scope and substance of the Franco—Polish partnership will depend primarily on the extent to which Paris and Warsaw are able to translate political commitments into concrete initiatives [5]. In this sense, the credibility of the obligations enshrined in the treaty will ultimately be tested by time and circumstances [1].

Experience suggests a cautious assessment. The conclusion of the Franco—German and Franco—Italian treaties has not fundamentally transformed bilateral relations nor eliminated their inherent structural problems [27, p. 26; 30, p. 28]. According to Donald Tusk, the Treaty of Nancy should, in the near future, be supplemented by a similar agreement with the United Kingdom, thereby elaborating a strengthened “dual” system of security guarantees for Poland in Europe. This, in turn, indicates that Warsaw does not yet regard the Treaty of Nancy as sufficient to achieve its core defence and security objectives. At the same time, historical experience cannot be ignored: “Anglo-­French security guarantees” were associated with a national catastrophe for Poland in September 1939 [31, p. 315—318] and remain embedded in Polish strategic culture more as symbols of unfulfilled promises than as examples of reliable commitments.

Against this background, the Polish expert community remains largely sceptical regarding the prospects for the effective implementation of the Treaty of Nancy, particularly following the election of President Karol Nawrocki, whose foreign-­policy orientation is expected to prioritise the strategic alliance with the United States. Such assessments of the treaty, combined with the limited practical effectiveness of similar European bilateral agreements concluded by France, raise broader questions about the underlying objectives of these arrangements.

The duplication of commitments and guarantees observed in these documents—many of which already exist within the NATO framework—appears to reflect a certain mistrust of collective allied obligations, shaped by both historical experience and contemporary foreign-­policy uncertainty. At present, the “reinsurance” function and symbolic significance of the Treaty of Nancy outweigh its tangible practical impact.

With regard to Russia’s relations with the European Union and NATO, the Treaty of Nancy may nevertheless signal a shift in France’s priorities in Eastern Europe, suggesting that Paris could increasingly focus its regional policy on Poland [3]. However, the treaty’s full strategic potential is likely to become clear only after a settlement of the conflict in Ukraine and the subsequent negotiation of a new framework for collective security in Europe involving Russia and Western states.