SARAJEVO, Bosnia-Herzegovina (AP) — The European Union’s enlargement commissioner urged Balkan leaders Thursday to stop stoking regional tensions and fully embrace their European future.

Johannes Hahn addressed the prime ministers of Albania, Bosnia, Kosovo, Montenegro, Macedonia and Serbia, who met in Sarajevo as part of preparations for a summit of some EU and western Balkan nations to be held in Trieste, Italy on July 12.

Hahn said the EU understood it was in its “hard-headed self-interest” to promote the troubled region’s future within the bloc when U.S policy for that part of the world is unclear and there are “unprecedented levels of involvement from further east” — an apparent reference to Russian meddling in the Balkans.

“We now have one of those windows of opportunity where either the region as a whole picks up momentum and we generate a genuinely positive narrative, or we end up in a really awkward spot, with a stream of bad news slamming the window firmly shut,” he said.

The Balkan countries are at different stages of being integrated into the bloc. Domestic politics and sluggish national economies have long hampered the EU integration of a region still recovering from the brutal wars of the 1990s.

Between an unresolved political crisis in Macedonia, a failed coup attempt in Montenegro, and growing discord between Bosnia’s ethnic leaders, the western Balkans now appear to be at their most tense in at least a decade

Relations between Kosovo and Serbia have also grown increasingly hostile, while an opposition boycott of Parliament in Albania is hampering that country’s ability to integrate with the EU.

Hahn acknowledged that the Sarajevo meeting was taking place at a point when several countries are undergoing “severe domestic political crises, sometimes heading toward serious ethnic tensions.”

However, he said the EU has “unequivocally confirmed” that the western Balkan countries have a future in Europe.

“I don’t think you can afford to squander this positive climate through domestic confrontations and blaming neighbors,” Hahn said. “This is playing with fire.”