Jean-Claude Juncker said after visiting Skopje, Tirana, Belgrade, Sarajevo, Podgorica, and Pristina that he "promised no one an accession date."

The European Commission president told Deutsche Welle that he also "didn't give states that are not yet negotiating a date to begin negotiations," adding that he was "not interested in fixing dates on a calendar as much as in substance."

"I care about dates, but not to the point that I would forget the substance in talks," said Juncker.

The accession conditions must be met, he continued - "which means the western Balkans states must drop their border conflicts. We can't import border conflicts into the EU. We must bring stability to the region, but instability can't be what we get in return."

The EU is also a community of values, he said, and added:

"The constitutional state, human rights, press freedom - these are all topics I sometimes have to explain a bit more thoroughly."

He assessed that "people in the EU are tired of enlargement" but that it was "important to explain that the western Balkans are on our doorstep."

"It's not far away, but the historic distance is long. Not too long ago, the region saw a fierce war. If we take away the western Balkans' accession perspective, that could soon repeat itself," Juncker said.