(Bloomberg Opinion) -- Amid much fanfare, French President Emmanuel Macron and German Chancellor Angela Merkel are about to sign a new treaty outlining a closer relationship between their two countries.

But the differences between the European Union’s mightiest powers are at least as pronounced as they were when Charles de Gaulle and Konrad Adenauer signed their declaration of the two countries’ friendship almost 56 years ago.

Macron and Merkel have scheduled the signing of the Aachen treaty for Jan. 22, the anniversary of de Gaulle and Adenauer’s Elysee original. In both cases, the initiative came from the French; both times, part of the motivation was standing up to the U.S.

Now, however, there are even stronger reasons than in 1963 for Germany and France to demonstrate their closeness. With the U.K. about to leave the EU, the bloc’s eastern flank in open mutiny, and Italy's far-right populists assembling a multinational euroskeptic alliance for May's election to the European Parliament, the European project needs a tougher core, and France and Germany need to show the resolve to form it. 

The draft treaty affirms the two countries’ intention to form joint positions on all important European issues. They also plan to harmonize their defense and arms export programs and work toward “a Franco-German economic area with joint rules.” In an interview with Sueddeutsche Zeitung, Michael Roth, the German foreign ministry official in charge of cooperation with France, spoke of making the border disappear for ordinary citizens. “This concerns schools, health care, the labor market,” he said.

The Elysee treaty was less ambitious: It was a mutual promise to cooperate. The Aachen one can be read as an attempt to show the entire EU a path forward, to insist on the somewhat battered ideal of an ever closer union. It may also be tempting for Macron, weakened by the gilets jaunes protests, and Merkel, in her lame duck phase, to step into the shoes of their great predecessors – and achieve more than they did.

In 1963, it quickly became apparent that French and German interests diverged. As part of the Elysee treaty’s ratification process, the German parliament added a preamble reaffirming the country's special relationship with the U.S. This moved de Gaulle to quip that “treaties are like girls and roses: They last while they last.” This time, Germany’s Atlantic commitments are unlikely to sour the deal: Donald Trump is even less popular in Berlin than in Paris. Other differences will, however, prevent Germany and France from forming a cohesive unit and presenting a strong positive example to other EU countries.

Germany wanted France to convert its seat on the United Nations Security Council to a European Union one; instead, the draft Aachen treaty says the diplomatic priority will be getting Germany a separate permanent seat. That, however, is likely to be impossible: Russia and China, both permanent members of the Security Council, can hardly be expected to support the addition of another Western nation to the five-strong club.

If France had been willing to cede its seat, incidents like the recent U.S. downgrading of the status of the European Union's mission to that of an international organization rather than a sovereign state would be less likely. As it is, the wording of the new treaty only supports the perception that, even for the core EU powers, national sovereignty trumps unity.

On military matters, cooperation will be as difficult. France and Germany formed a joint brigade back in 1989, but it still has no mixed companies and soldiers train according to national standards and use different weapons. The troops are deployed in Mali now, but while the French soldiers are involved in anti-terrorist missions, their German counterparts only take part in training the local military. It’s not the absence of a better friendship treaty that has stopped the brigade from gelling, but the cultural differences between the two countries’ forces.

These differences exist on the security policy level, too. In October, following the murder of Saudi journalist Jamal Khashoggi, tensions arose over the two countries’ joint New Generation Fighter project. France insisted that the new jets should be freely exportable to all countries, while Germany advocated more responsibility in picking buyers. It won’t be easy to find a joint approach to arms exports, as the nations promise each other in the draft treaty.

An economic area with common rules comprising big-spending France with its perpetual deficits and Germany with its consistent surpluses is also hard to imagine. The two countries haven’t even been able to agree on a clear matter of common economic interest – the taxation of digital companies. Last month, they hammered out a compromise, calling on the EU to impose a levy on digital ad revenue by 2021 unless a broader international solution is found by then. But if France and Germany were really interested in leading the way, they’d have introduced a tax themselves, without waiting for anyone else. 

Symbolic expressions of solidarity are important in these times of disunity and fracturing. But in real life, working together is tough even for partners with the best of intentions. Macron and Merkel would do better to pick and publicize a series of specific, new joint projects than to renew de Gaulle and Adenauer’s old vows. Then, perhaps, others would be easier to convert to the idea of ever closer union.

To contact the author of this story: Leonid Bershidsky at lbershidsky@bloomberg.net

To contact the editor responsible for this story: Edward Evans at eevans3@bloomberg.net

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Leonid Bershidsky is Bloomberg Opinion's Europe columnist. He was the founding editor of the Russian business daily Vedomosti and founded the opinion website Slon.ru.

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