Serbs put up new roadblocks as tensions soar in Kosovo.

Serbs on Tuesday erected more roadblocks in northern Kosovo and defied international demands to remove those placed earlier, a day after Serbia put its troops near the border on a high level of combat readiness.

The new barriers, made of heavily loaded trucks, were put up overnight in Mitrovica, a northern Kosovo town divided between Kosovo Serbs and ethnic Albanians, who represent the majority in Kosovo as a whole.

It was the first time since the recent crisis started that Serbs have blocked streets in one of the main towns. Until now, barricades had been set on roads leading to the Kosovo-Serbia border.

Serbian President Aleksandar Vucic has said he ordered the army’s highest state of alert to “protect our people (in Kosovo) and preserve Serbia.”

He claimed that Pristina is preparing to “attack” Kosovo Serbs in the north of the country and remove by force several of the roadblocks that Serbs started putting up 18 days ago to protest the arrest of a former Kosovo Serb police officer.

On Tuesday, Vucic addressed reporters together with Serbian Patriarch Porfirije, who was barred by Kosovo authorities on Monday from entering Kosovo and visiting a medieval Serb church there before Serbian Orthodox Christmas, which is celebrated on Jan. 7.