U.S. President Donald Trump has urged Kosovo to do everything to reach a long-standing deal with Serbia two decades after their war ended, according to the Kosovo president's website.
In a letter sent to President Hashim Thaci and posted on Thaci's official page on December 18, Trump says, "Failure to capitalize on this unique opportunity would be a tragic setback, as another chance for a comprehensive peace is unlikely to occur again soon.
"The United States has invested heavily in the success of Kosovo as an independent, sovereign state," the letter said. "I look forward to hosting you and [Serbian] President Aleksandar Vucic at the White House to celebrate what would be an historic accord."
There was no immediate comment on the letter from the White House or from the U.S. Embassy in Kosovo's capital, Pristina.
Kosovo declared independence from Serbia in 2008.
Although more than 110 countries recognize Kosovo, Serbia does not.
In 2013, Pristina and Belgrade committed to a European Union-sponsored dialogue meant to resolve all unsolved issues but little progress has been made.
Tensions rose again last week when Kosovo's parliament voted to approve the creation of a 5,000-strong standing army -- a week after Belgrade suggested such a move could provoke a military intervention by Belgrade.
Speaking in Brussels on December 19 after attending a lunch for five Western Balkan leaders, Kosovar President Hashim Thaci said: "I believe strongly that in the next weeks and months we will be able to conclude the process of reaching an agreement with Serbia."
However, his Serbian counterpart, Aleksandar Vucic, disagreed, telling reporters: "I don’t think we are close to an agreement."
EU foreign policy chief Federica Mogherini, who hosted the gathering, said in a statement that the five Balkan leaders -- who also included Bosnian Prime Minister Denis Zvizdic, Macedonian Prime Minister Zoran Zaev, and Montenegrin President Milo Djukanovic -- "expressed the strongest support" for a comprehensive, legally binding agreement between Pristina and Belgrade.
They also vowed to refrain "from all actions and statements that are not conducive to the overall interests and strategic objectives of the region," the statement said.