Nato troops made a tactical retreat in Kosovo as ethnic Serbs stopped them reaching peacekeepers deployed at border posts with Serbia after a customs dispute turned violent.
Hundreds of Serbs used trucks, trailers and logs to block access roads. But General Erhard Buehler warned the situation could not continue.
“There will not be a second time. The next time we will be blocked I have to use force and everybody will understand it,” he said.
The border posts of Bdnjak and Jarinje had been staffed mostly by ethnic Serbs. But on Monday Pristina sent ethnic Albanian special police to take over.
That sparked three days of violence in which an Albanian policeman was shot dead.
Pristina’s decision to send special police came as part of an ongoing dispute with Belgrade over customs regulations.