Mujtaba Rahman is the head of Eurasia Group’s Europe practice. He tweets at @Mij_Europe.

An age-old French nightmare — that of growing German military might — is resurfacing in a new form.

Indeed, 19th and 20th century anxieties over a cross-Rhine invasion have long been obliterated by the Franco-German partnership within European and Atlantic alliances. Moreover, Berlin’s current plans to double defense spending is welcomed in France as a bulwark against both Russian aggression and U.S. disengagement.

Yet, according to anonymous government officials, French President Emmanuel Macron is said to be “obsessed” with the huge fiscal freedom Germany possesses to rearm itself over the next five years, especially compared to cash-strapped France.

He fears an invasion — not of French territory, but of his country’s preeminent position as the EU’s most effective military-diplomatic power. He’s also worried about whether Germany’s billions will be used to build or blur his vision of a strategically autonomous European defense industry.

In theory, both countries are bound by NATO members’ new pledge to spend 3.5 percent of GDP on defense by 2035. But while Germany has a credible plan to reach that target by 2029, short of vast grants from an EU defense fund that may never exist, France has no obvious way to both honor its NATO commitment and cut its budget deficit to 3 percent of GDP in four years.

Given the disparity between their GDPs and populations, this year’s German and French defense budgets are roughly comparable — €86 billion in Germany and €62 billion in France. By 2029, however, Germany expects to be spending €150 billion a year; while France, even with its newly expanded defense plans, will be spending €80 billion at best.

Still, some senior French officials who spoke on condition of anonymity dismissed fears that Germany’s new military might — and to some extent Poland’s — will erode Paris’ clout in Brussels. They argued that France’s “special” status within the EU is also borne of its global military reach, its permanent U.N. Security Council membership and its nuclear deterrent.

French military chiefs who asked to remain unnamed were also dismissive of the Bundeswehr’s capacity to become an efficient force after eight decades of historical aversion to all things military. They said the catch-up spending is welcome and important, but it will be many years before the German army and air force can match France’s.

The more immediate problem, however, is the direction of travel. Will the German military build-up help forge a more strategically autonomous European defense industry, create European jobs and strengthen European economic power? Or, will it pour money into off-the-shelf U.S. military hardware and favor industrial alliances with American defense giants?

At times, German Chancellor Friedrich Merz echoes Macron on the matter, saying that the surge in his country’s defense spending must have a European “framework” and promote “European strategic sovereignty.” On other occasions, he has spoken of a “coalition contract” within NATO and the importance of the transatlantic partnership.

Either way, the sheer scale of Berlin’s spending in the years ahead will inevitably make its defense industry the key player in European military innovation and procurement. And in the past, much of Germany’s industry preferred to seek partnerships with the U.S. or turn to German start-ups rather than cooperate with established players in France or other EU countries.

Sticking to this old pattern, Paris was dismayed by Rheinmetall’s recent decision to enter an agreement with the U.S. company Anduril to produce drones and missiles. But while it may be too late to wean Germany off U.S. warplanes, the truth is, there can never be a solid European military-industrial base unless EU countries come together to develop the weapons of the future.

It is, therefore, vital that Berlin and Paris immediately establish a pattern for the upcoming boom years, and double down on their political commitment to Franco-German cooperation in defense innovation, training and procurement. The window of opportunity is narrow — and afterward, there will only be room to implement the decisions already made.

The majority view in Paris is that German rearmament will raise these questions of “industrial balance” long before it raises issues of “political balance” within the EU. But Merz also understands that unless it’s embedded in a European consensus, Germany’s military might could become a political problem — and not just for the French.

Nonetheless, France will be looking at the decade ahead anxiously, as Germany will retain its status as Europe’s industrial powerhouse, as well as become — just by sheer size — the dominant military power within the EU.

The uncomfortable truth for France is that when it comes to the creation of a European defense industry, and even the potential rapid increase of France’s own military capacity, strategic autonomy is now in Germany’s hands.