Serbian media quoted Balkan experts Florian Bieber and Tim Judah, who expressed surprise at the announced appointment of Richard Grenell as special envoy for negotiations.

Professor at the University of Grazz, Bieber wondered what the role of Matthew Palmer was, the recently appointed US Secretary of State's Special Representative for the Balkans.

"If Trump appoints Richard Grenell as special envoy for Serbia and Kosovo, what than is the role of Matthew Palmer?" Bieber wrote on Twitter.

He added that it was also "a worrying message for the EU-US Common Position".

Grenell as an ambassador has a history of alienating Germany and the EU, Bieber said, citing Grenell's call for support for the right and the extreme right.

"Not a good sign," Bieber writes.

British journalist and analyst Tim Judah said on Twitter that Grenell's appointment was "strange".

"This is weird. First the US appoints the well-respected Matt Palmer who knows the region and its leaders well as Balkan envoy and now someone else with no Balkan track record or knowledge as far as we know to Serbia-Kosovo talks. Smacks of complete incoherence," Judah said.

He estimated that all seemed completely unrelated.