Suddenly, the debate about creating a joint European Union army has gained real momentum. After French President Emmanuel Macron recently proposed the idea, US President Donald Trump disparaged it (in a tweet ^[1], of course), but German chancellor Angela Merkel endorsed it ^[2] (while urging caution).

The issue came to the fore this month with the centennial of the end of World War I, which naturally focused Europeans’ attention on matters of war and peace. While touring WWI battlefields, Macron observed ^[3] that ‘peace in Europe is precarious’, and that ‘we will not protect Europeans unless we decide to have a true European army’.

The goal of establishing a European army dates back to the earliest stages of European integration after World War II. In 1954, the French parliament refused to ratify a treaty that would have established a European Defence Community and joint military force comprising West Germany, France, Italy, Belgium, the Netherlands and Luxembourg. After that, the structures of integration that would eventually underpin today’s EU tended to be more economically oriented, and territorial defence was left to NATO and the US security umbrella.

But over the last few decades, there has been more movement towards establishing a common EU foreign and security policy, and new structures and institutions have been developed with that goal in mind. Still, today’s discussion of European defence is truly novel. Until now, the EU has primarily fostered cooperation in the area of research and development, while various country groupings have worked to establish different defence and security capabilities. In the next seven-year budget, there will likely be substantial funding for such projects.

Macron is right to think that the EU’s strategic environment has become increasingly fragile. Europeans today are confronted with a revanchist Russia, an assertive China, and a disruptive US. Although the US has expanded its military capabilities in Europe in recent years, it has previously regarded the continent primarily as a platform for operations in other theatres. And now that Trump has cast doubt ^[4] on America’s commitment to defend Europe, renewed proposals for a European army should come as no surprise.

Still, Europe is home to only three countries with a robust strategic culture: France, the United Kingdom and Russia. All three have a deep-seated institutional understanding of geopolitical power dynamics and the use of military force. Indeed, Russia’s own program of military modernisation suggests that it is becoming increasingly reliant on hard power to pursue its interests.

Meanwhile, France has launched the European Intervention Initiative ^[5], a new framework uniting countries with real defence capabilities and a willingness to use them. Most important, this new grouping will include the UK even after it leaves the EU. That said, Macron’s vision of a European army under a central EU-level command will remain aspirational for the foreseeable future, for the simple reason that countries seldom give up their armies voluntarily.

Nonetheless, it is worth considering Macron’s broader goal, which extends well beyond immediate concerns such as Trump and Brexit. In short, Macron is calling on Europe to develop a more coherent and autonomous strategy for pursuing its security and defense interests in the twenty-first century.

Needless to say, this project will encounter many hurdles. Russia’s use of nuclear forces can be deterred only by those of the US ^[6]. The French and the British don’t like to admit it, but their nuclear arsenals are simply insufficient, especially now that Russia is upgrading its own. Beyond nuclear deterrence, the US will also likely remain at the center of command, control, and intelligence when it comes to continent-wide operations.

Moreover, Europeans will also have to resolve a number of internal tensions. Germany will insist that all new programs be housed within EU structures, while demanding parliamentary approval for all operations. But the British will no longer belong to the EU, and will remain sceptical of French talk of strategic autonomy, which could imply a weaker NATO. The same goes for eastern EU member states, which are even less willing to countenance a delinking from NATO or the US.

Despite these difficulties, there is an emerging consensus on the need to restructure European defence. The ostensible impetus is the growing threat from Russia, China and the broader Middle East. But the uncomfortable reality is that renewed interest in military integration also reflects the erosion of Europe’s strategic position as a result of Brexit and, in some respects, Trump.

I expect that a French army—not a European one—will be marching down the Champs Elysées on Bastille Day for decades to come. But I also expect European countries to become more assertive in defence of their sovereignty, and to act collectively when it comes to security.