From the refugee crisis to security threats, Europe’s biggest challenges pass through the Western Balkans. But officials worry that Brexit will see the EU turn inwards just as Russia’s influence in the region is on the rise.

“Serbia will join the EU during Turkey’s presidency” is a running joke in Belgrade. But the growing sense that the country may never get to join the union is no laughing matter. Just two decades ago, the Western Balkans were terrain of genocide, and of the largest conflict and displacement of people on European soil since the end of the second world war.

For the nations that once comprised Yugoslavia, the promise of EU membership became a cause for both governments and electorates to get behind. It is a promise that contributed to bringing war criminals to justice, and one that has helped to keep the past in check, curbing nationalism and religious and ethnic tensions across the region. The prospect of joining the European Union charted a pathway of reforms that has kept alternative roads at arm’s length.

Two, Slovenia and Croatia, have already joined the EU. Three are candidates to join – the former Yugoslav Republic of Macedonia, Montenegro, and Serbia – while Bosnia and Herzegovina hopes to do so one day. As does Kosovo, even though some EU member states still don’t recognise it as independent.