The United States and its allies criticized Kosovo on Friday for escalating tensions with Serbia, stating that the use of force to install mayors in ethnic Serb areas undermined efforts to repair relations with Serbia.

Following confrontations between Kosovar police and demonstrators opposed to the ethnic Albanian mayors, Serbian President Aleksandar Vucic placed the army on full combat alert and ordered units to advance closer to the border.

US Condemns Kosovo Government

After a vote in April was boycotted by the Kosovo Serb majority in four northern municipalities near the Serbian border, police in the town of Zvecan used tear gas to disperse a throng attempting to prevent a newly-elected mayor from entering his office.

Secretary of State Antony Blinken of the United States criticized the Kosovo government for forcibly entering municipal buildings and urged Prime Minister Albin Kurti to reverse course.

Blinken said that Kosovo's actions were contrary to US and European advice and had "sharply and needlessly escalated tensions, undermining our efforts to help normalize relations between Kosovo and Serbia, and will have repercussions for our bilateral relations with Kosovo."

The United States, Britain, France, Italy, and Germany issued a joint statement urging Kosovar authorities to withdraw and de-escalate the situation, Reuters reported.

Per AOL, several vehicles were set on fire after police in Kosovo launched tear gas. The throng was dispersed with tear gas so that the new officials could enter their offices. According to Kosovo Serb hospital officials, approximately 10 demonstrators were injured.

Five police officers were injured by stun grenades and other projectiles hurled by demonstrators, according to the police. A police vehicle was set ablaze. Additionally, Vucic demanded that NATO-led forces stationed in Kosovo defend ethnic Serbs from Kosovo police. The United States condemned the Kosovo government's use of police to infiltrate municipal buildings by force.

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Kosovo Serbs Clash with Police

Vucic spoke at a rally in Belgrade on Friday evening as tens of thousands of people gathered to support the government in the aftermath of two shocking mass shootings earlier this month that left 18 people dead and 20 others wounded.

He has previously warned that Belgrade would respond to violence against Serbs, and he has repeatedly increased combat readiness during periods of heightened tension with Kosovo. Any attempt by Serbia to cross the frontier, however, would result in a confrontation with NATO troops stationed there.

Former Serbian army chief and current opposition politician Zdravko Ponos criticized Vucic's response as "inappropriate." Ponos stated on the N1 regional television network, "This is merely Vucic's attempt to save dignity through bluster."

The Kosovo police acknowledged their enhanced presence in the north "to aid the mayors of Zvecan, Leposavic, and Zubin Potok in exercising their right to work."

Small groups of Serbs reportedly raised their palms at the entrances of municipal facilities in three northern communities to demonstrate that they were not there to engage in violence, as reported by the Albanian news website indexonline.net, which also published photographs.

In Zvecan, the Kosovo-online.com website depicted police confrontations in front of the public building, while in Leposavic, the main square was obstructed by vehicles. Earlier, Serbs activated their alarm sirens in the four communes, including the principal northern town of Mitrovica, as a warning signal and rallying call, as per Aljazeera via MSN.

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