Serbia and Kosovo have begun a combined operation to staff two border crossings in the first joint-venture of its type since the war between the two ended in 1999.
The force of police and customs officers has been brokered by the EU, and European officers from the Eulex police feature heavily in the mix too.
The new border posts are at Jarinje and Merdare. There are six crossing points between Kosovo and Serbia in all. There are plans to open two more by the end of the year.
Radojko Stefanovic was the first across at Merdare, saying it was good because there were no delays nor traffic problems.
The predominantly Serb north of Kosovo has been a tinderbox since the Albanian majority unilaterally declared independence from Serbia.
Serbia refuses to recognise Kosovo as an independent state but is under pressure from the EU to cooperate with Pristina if it wants membership talks to progress.