Brussels has again told Serbia it can't sit on several chairs at once. The European Parliament's rapporteur for Serbia, Tonino Picula, said openly that the country can't become an EU member if it keeps its partnerships with Russia and China. A message that sounds to Belgrade like an ultimatum - and to the rest of the Balkans like a familiar film.

"A state that tries to sit on three or four chairs can't maintain that illusion for long," Picula said, referring to Serbia's so-called multi-vector policy. According to him, Belgrade "must decide for itself" - whom it goes with and where it belongs. He also expressed concern over a possible strategic partnership between Serbia and the US, with the logic that you can't please everyone at the same time.

Serbia has been a membership candidate for years, but unlike most of the EU, it didn't impose sanctions on Russia. That is precisely the core of the dispute. On one hand, the demand is legitimate - membership in the club means playing by the club's rules. On the other, the question Belgrade raises isn't without basis: why does choosing always go only in one direction, and why do the terms keep changing on the go?

Here it's worth separating two things. EU pressure is a real and legitimate part of the negotiation process - it's not a conspiracy. But the way it's packaged, as a lesson from mentor to pupil, provokes no flat reaction anywhere in the Balkans. The region knows that dynamic all too well - the "approaching" that lasts for decades, the conditions added every year, the promises that come with no date.

The question left open isn't whether Serbia will decide, but how sincere what's offered from the other side actually is. Because "we wait at the EU's door like at a municipal counter" is a sentence that, in this part of the world, needs no explaining to anyone.