European Union leaders have suddenly awoken to new realities in the Balkans. At a recent summit, they emphasised the need for increased EU engagement to maintain stability—and to push back against Russian influence—in the region.

But the Balkan countries’ geopolitical situation should not come as a surprise. After all, post-Ottoman fractures—stretching from Bihać in Bosnia’s northwestern corner to Basra on Iraq’s Persian Gulf coast—have repeatedly been a source of regional and global instability since the demise of the old empires a century ago.

When the Habsburg and Ottoman empires collapsed at the end of World War I, attempts were made to establish modern nation-states in the Balkans, despite the region’s national and cultural diversity. Since then, nationalism has repeatedly clashed with the region’s enduring mosaic of civil life, fueling one conflict after another.

Yugoslavia, like the nation-states that were established in the Levant and Mesopotamia, was created to manage these political contradictions; but atrocities—in Smyrna, Srebrenica, Sinjar, and elsewhere—remained a constant feature of post-imperial life.

Yugoslavia collapsed in the early 1990’s, triggering a decade of brutal wars from Croatia to Kosovo. The emergence of seven new—and often mutually antagonistic—states made it clear that regional stability would depend on a new framework, namely, the EU. Owing to its success in settling other longstanding national conflicts, the EU was tasked with bridging the region’s longstanding nationalist divides and quelling its ethnic conflicts.

At an EU summit in Thessaloniki in 2003, delegates solemnly vowed to bring all of the Balkan countries into the bloc as members. That promise would be as hard to keep as it was important to make. When the Balkans’ immediate problems had subsided, EU leaders assumed that they had secured peace for the region. Henceforth, their business-as-usual approach to the Balkans essentially meant maintaining the status quo.

After Jean-Claude Juncker was appointed European Commission President in 2014, he confirmed the status quo, by declaring that the EU would undergo no further expansion during his five-year term. Juncker’s statement was technically correct, but politically disastrous. With the light that had been guiding reform and integration efforts now extinguished, nationalism in the region predictably started to rise again. And the EU, meanwhile, became fixated on its ongoing financial problems, such as member-state sovereign-debt crises.

I spent a lot of time in the Balkans in the years after the Bosnian War. I was the EU’s Special Envoy to the Former Yugoslavia, then Co-chairman of the Dayton Peace Conference, High Representative for Bosnia and Herzegovina, and, finally, the United Nations Secretary-General’s Special Envoy for the Balkans.

Last year, when I returned to Bosnia in an unofficial capacity, someone asked me if war was coming back to the region. At first, I shrugged off the question. ‘No way,’ I responded. But then others kept posing the same question; by the fifth time, I started becoming concerned.

I was certainly right to say that the wars of the 1990’s will not come back: the conditions today are very different from what they were then. But, as we have seen many times before, individual hotheads can ignite fires that are difficult to contain. Once upon a time in Sarajevo, a single person named Gavrilo Princip triggered a world war when he assassinated Archduke Franz Ferdinand of Austria. Today, the region is gradually becoming more combustible, and another spark could be lit, perhaps this time in Skopje.

So what is to be done? For Europe, the only way forward is to assert its powers of containment, while also accelerating European integration. To address the emerging risks in the Balkans, the EU should demonstrate that it has the will and means to act, by deploying EU Battle Groups to conduct military exercises in the region. This would send a powerful message that its military forces are not paper tigers, and that it is capable of wielding more than just words.

Further EU enlargement is also imperative. With only Slovenia and Croatia having joined the bloc so far, securing membership for the remaining Balkan countries obviously will take time. But the reforms needed to make these countries eligible for membership can and should be accelerated, with interim steps that have credibility with the region’s people.

For example, we should replicate the EU Eastern Partnership, with the creation of a Balkan Partnership, while always keeping membership on the table. At the same time, the EU needs to step up its political engagement in the region. It can start by mediating outstanding minor border disputes, so that these are not left to fester.

The EU, in today’s parlance, has a bandwidth problem: its challenges have multiplied in recent years, as have the summits it holds to address them. But European leaders have an obvious choice in the Balkans: either deal with the problem, or wait for it to deal with them.