Twenty years after the wars the region is peaceful and all the countries strive to become EU members. "The significant progress achieved, however, should not be taken for granted," Frank-Walter Steinmeier and Sebastian Kurz write, noting that the region's stability still rests "on shaky foundations" and largely depends on EU support.

The op-ed comes ahead of the Vienna Summit, the second in a series of five summits planned until 2018, which is part of the Berlin Process initiated by Germany and now carried over by Austria.

Steinmeier and Kurz say the summit has three main objectives: to highlight the substantial progress achieved in the region, to reconfirm the EU perspective of all countries of the region, and to accelerate reforms and encourage regional cooperation.

At last year's summit the regional leaders agreed to focus on specific, tangible projects, including a regional core transport network as a backbone of economic development.

This year a regional youth exchange initiative, based on the Franco-German and Polish-German models, will be presented. It should contribute to tearing down the still existing walls in the minds of young people and foster reconciliation, the op-ed says.

The conference will also pay particular attention to the fact that the Western Balkan route has become the primary route of a growing number of refugees heading to the EU.

"These developments create significant challenges for border management and asylum systems in some Western Balkan countries as well as in EU member states. Western Balkan countries too will have to assume their responsibilities to address these challenges."

"But they are not alone: We will discuss in Vienna how the European Union as well as individual EU member states can support Western Balkan countries in their efforts to improve border management and asylum systems," Steinmeier and Kurz note.

In general, the summit will "renew our firm commitment to the European perspective for all the Western Balkan countries".

"The door to the EU must remain open for the Western Balkans in order to ensure that the EU remains the most successful peace project in the world. Without the Western Balkans, the EU is clearly incomplete."