Paris and Warsaw are set to accelerate their military cooperation, with both capitals now bound by a “solidarity clause” that could extend to nuclear deterrence should the vital interests of either country be threatened.

Presidents Emmanuel Macron and Donald Tusk today signed a treaty of friendship and enhanced cooperation in Nancy, highlighting Poland’s growing strategic importance on the eastern flank of the European Union (EU).

This bilateral treaty is the first of its kind signed by Paris with a non-neighbouring country, following similar agreements with Germany (1963), Italy (2021), and Spain (2023).

“We have decided to send a very clear signal by including [in this treaty] a clause on mutual defence and assistance, building on our shared commitments within NATO and the European Union,” explained the French president.

This defence clause “encompasses all components” of the two countries’ military capabilities, Macron added, emphasising that the vital interests of France’s “main partners” are considered part of its own vital interests.

In early March, Macron had already expressed willingness to “open discussions” on extending France’s nuclear deterrent to certain European countries. Paris is reportedly considering increasing its nuclear arsenal.

The Treaty of Nancy is intended to foster deeper collaboration between the French and Polish armed forces, through regular meetings between their general staffs, joint exercises, and, most importantly, the “implementation and development of joint projects” in the field of armaments.

Europe’s leading land army

With Warsaw already devoting more than 4% of its GDP to defence, Poland aims to become the leading land military power in Europe by 2035, with an army projected to exceed 300,000 troops.

This will generate “significant training needs”, and Poland could draw on the experience of the French military, notes Léo Péria-Peigné, a defence industry expert at the French Institute of International Relations (IFRI) and co-author of a study on Polish rearmament.

For Paris, this move aligns with its broader “pivot towards Europe”, following the withdrawal of French troops from the African continent and the deployment of several hundred troops to Romania and Estonia. French authorities have stated their aim of playing a central role in the future European security architecture.

Forging a strong partnership with Warsaw could also open new markets for France’s defence industrial and technological base (BITD), at a time when Poland currently relies primarily on the United States and South Korea for its defence procurements.

Last year, the Polish army ordered 96 Apache attack helicopters and 48 Patriot missile launchers from Washington. In recent years, Poland has also acquired howitzers, tanks, and aircraft from South Korea.

“We will gradually introduce a preference for European suppliers in the defence industry,” Tusk promised on Friday.

The Weimar Triangle at the heart of Europe

The signing of the Treaty of Nancy marks a significant improvement of relations between Paris and Warsaw, which began with the defeat of the nationalist PiS party in the 2023 Polish parliamentary elections. Ties between France and Poland were severely damaged in 2016 by the cancellation of a contract to supply the Polish army with 50 H225M Caracal helicopters, manufactured by Airbus.

The agreement also coincides with the early initiatives of newly elected German Chancellor Friedrich Merz, who visited Paris and Warsaw just hours after his election and appears keen to anchor his European policy around the “Weimar Triangle” partnership.

(aw)