After protesting Serbs in its north vowed to remove obstacles, Kosovo reopened its busiest border crossing with Serbia on Thursday, calming rising tensions that had frightened foreign powers.

Serbia and Kosovo have been under pressure from the European Union and the United States to back off from an escalating conflict that has seen Serbia raise its army’s battle readiness level.

Since Dec. 10, Serbs in northern Kosovo have been blocking roads in protest of a former Serb policeman’s arrest, the most recent in a string of flashpoints. However, once he was placed under house arrest, they agreed to start removing the obstacles.

Many of the roadblocks still appeared to be in place on Thursday morning, though officials had said the process might take some time.

Tensions remained high. Two burned-out trucks filled with gravel stood on a bridge close to the ethically divided town of Mitrovica, some 50 km from the reopened Merdare crossing. Kosovo police said they were investigating an arson attack.

Around 50,000 Serbs living in northern Kosovo refuse to recognize the government in Pristina or the status of Kosovo as a separate country. They have the support of many Serbs in Serbia and its government.

Albanian-majority Kosovo declared independence with the backing of the West following a 1998-99 war in which NATO intervened to protect ethnic Albanian citizens.

Kosovo police said they had reopened the Merdare crossing – the most important for road freight that links the landlocked state with western European countries – after roadblocks came down on the Serbian side of the border.

They called on people from the diaspora to use the crossing, which was closed at midnight on Tuesday, to come home for the holidays.

Since December 10, two border crossings with Serbia in Kosovo’s north are still closed.

Kosovo has long been a point of contention between the West, which supported Kosovo’s independence, and Russia, which backs Serbia in its efforts to prevent Kosovo from joining international organizations like the UN.

On Wednesday, the Kremlin rejected claims made by the interior minister of Kosovo that Serbia was being influenced by Russia to destabilize Kosovo and that Serbia was instead standing up for the rights of ethnic Serbs.