Europe’s deepening military cooperation, France and Poland signed a landmark mutual defense treaty on Friday, committing both nations to provide military assistance to one another in the event of an armed attack. The agreement, inked in the symbolic eastern French city of Nancy, was hailed by leaders on both sides as a “historic” step in fortifying European security in the wake of Russia’s continuing aggression in Ukraine.
French President Emmanuel Macron and Polish Prime Minister Donald Tusk, two of Europe’s most vocal supporters of Kyiv since Russia’s 2022 invasion, formalized the treaty during a joint press conference, emphasizing their nations’ readiness to respond swiftly to any threat to their sovereignty.
“This treaty reinforces what already exists today under NATO and the EU,” Macron stated. “It is not a substitute. It’s a strategic deepening—a clear message that we will not be passive if Europe is attacked.”
While both France and Poland are long-standing members of NATO and the European Union, this new bilateral accord goes beyond symbolic unity. The treaty explicitly includes a “mutual defense clause” stating that “in the event of armed aggression on their territories, the parties shall provide mutual assistance, including by military means.”
Macron confirmed that this could involve the rapid deployment of troops: “I have no doubt that yes, such a deployment would be possible in the face of aggression and if the worst were to happen.”
Importantly, Macron also implied that France’s nuclear arsenal—unique among EU member states—could be considered part of its defense umbrella, depending on the threat.
“Our nuclear doctrine includes the defense of vital interests,” he said. “Those interests now integrate the broader security of our main European partners.”
For Poland, which shares borders with both Russia’s Kaliningrad exclave and Belarus, the treaty offers a strategic safeguard amid ongoing regional instability and growing fears that Russia could test NATO’s eastern flank in the future.
“This is a historic event,” said Tusk. “France and Poland can count on each other in all circumstances—good and bad.”
The Franco-Polish treaty reflects a broader shift in European defense thinking. With war continuing in Ukraine and doubts lingering about future U.S. commitments—especially under the possibility of a second Trump presidency—many European leaders are taking steps to boost continental military self-reliance.
President Joe Biden’s administration recently floated a proposal for a 30-day ceasefire between Ukraine and Russia, though analysts suggest the Kremlin remains disinterested in any real de-escalation. Macron echoed this concern, calling Russian President Vladimir Putin’s recent statements “belligerent.”
“President Putin is on the side of war, not peace. His comments and actions speak for themselves,” Macron said, referencing Putin’s remarks during the Victory Day parade in Moscow.
Tusk, speaking with unusually sharp language, criticized fellow EU leaders who chose to attend the Moscow celebrations—widely seen as a Kremlin propaganda event. Without naming names, he said, “Being at that parade brings shame.”
Slovakia’s Prime Minister Robert Fico was among the European leaders in attendance, alongside China’s President Xi Jinping. The contrast between Fico’s appearance in Red Square and the Macron–Tusk summit in Nancy underscored the growing rift between pro-Ukraine EU states and those drifting closer to Moscow.
The choice of Nancy as the signing venue was not coincidental. The city sits in the Lorraine region, once ruled by Poland’s deposed King Stanislaw I in the 18th century. Stanislaw’s daughter was married to King Louis XV of France, and Nancy’s central square—Place Stanislas—is named in his honor.
This shared history lent emotional gravity to the occasion, connecting past Franco-Polish ties with today’s renewed alliance. It was a deliberate reminder that the two nations’ fates have long been intertwined, especially in times of conflict.
Poland is not only seeking symbolic alliances. It is rapidly growing its military capabilities and could soon possess the largest army in the European Union. As of 2024, Poland had 216,000 active troops, according to NATO estimates—surpassing France’s 205,000 and Germany’s 186,000. Warsaw aims to boost this number to 300,000 by 2035.
This expansion is driven by urgent security calculations. Polish officials have repeatedly warned that the country could become a target for Russian aggression, particularly given its proximity to Kaliningrad and its role as a logistical hub for military aid to Ukraine.
The treaty with France sends a powerful signal: Poland is not alone, and it is aligning itself with the EU’s most formidable military power.
“This is about deterrence as much as solidarity,” said Katarzyna Pisarska, a foreign policy analyst at the Warsaw Security Forum. “Poland’s concern has always been whether Western Europe would come to its aid in time. This treaty makes that promise more concrete.”
The agreement also marks a political thaw between France and Poland. Under the previous nationalist Law and Justice (PiS) government, relations with France had grown chilly, marred by disputes over the rule of law, media freedoms, and defense cooperation.
Since taking office in late 2023, Donald Tusk has shifted Poland firmly back into the European mainstream. A former president of the European Council, Tusk has prioritized rebuilding ties with Brussels and Paris, and this treaty is perhaps the most tangible outcome of that strategy.
“We are in a new phase,” said Macron. “This partnership is built on trust, responsibility, and a shared vision for Europe’s future.”
The timing of the treaty is also notable for Poland’s domestic political calendar. The country is heading into presidential elections on May 18. The vote is expected to be a fierce contest between a pro-European candidate, Warsaw Mayor Rafał Trzaskowski—backed by Tusk—and a nationalist challenger supported by the PiS.
There are growing concerns about Russian interference. Polish intelligence has warned of disinformation campaigns aiming to divide the electorate and cast doubt on Poland’s alliances. Officials have already detected online influence operations targeting military aid to Ukraine and casting Tusk as a “foreign puppet.”
Signing the treaty just days before the election may serve to boost Tusk’s European credentials and blunt nationalist attacks accusing him of subordinating Polish sovereignty to Brussels.
The Macron–Tusk summit took place one day before a planned gathering in Ukraine of what President Volodymyr Zelensky has termed a “coalition of the willing”—a group of European nations pledging enhanced support for Kyiv. Zelensky did not name participants, but Poland and France are expected to feature prominently.
Analysts say the Franco-Polish pact is likely to be a blueprint for similar bilateral or multilateral arrangements across Europe. With faith in U.S. security guarantees ebbing and transatlantic politics in flux, the EU may find itself forced to take on more of its own defense burden.
“This is the beginning of a more autonomous European defense architecture,” said Bruno Tertrais, deputy director of France’s Foundation for Strategic Research. “Not replacing NATO, but complementing it—especially in a world where American priorities may shift.”
At a time of growing geopolitical turbulence, the France–Poland defense treaty is more than a diplomatic gesture. It is a clear and calculated response to a worsening security environment, an assertion that Europe will not wait passively for the next crisis to erupt.
With war on its eastern doorstep, political uncertainty in Washington, and rising authoritarianism within its own ranks, the European Union faces a historic inflection point. The message from Nancy was simple, yet forceful: Europe is watching each other’s backs.
