The leaders of Kosovo and Serbia will have to make "difficult compromises" to normalize their relations, U.S. Secretary of State Antony Blinken said Wednesday.

"I am confident that normalization of relations between Serbia and Kosovo will bring security and prosperity for Serbia and all citizens of the Western Balkans," Blinken said in a statement on the State Department website.

"Certainly, Serbian and Kosovan leaders will make difficult compromises to achieve these goals, but the rewards for the Serbian people – and the entire region – will be vast," Blinken said, congratulating Serbia as it marked its Statehood Day on Wednesday.

Blinken also urged Serbia to "to support Ukraine against Russia's unprovoked, unjustified, and brutal war".

U.S. and EU envoys have insisted that the two countries endorse a peace plan, presented in mid-2022, under which Belgrade would stop lobbying against giving Kosovo a seat in international organizations, including the United Nations.

Kosovo will undertake to form an association of municipalities with a Serb majority in accordance with these proposals.