Previous negotiations lasted several years without much progress before stalling in 2018, after the government of Prime Minister Ramush Haradinaj of Kosovo imposed 100 percent tariffs on imports from Serbia and passed legislation to form an army.
Mr. Haradinaj resigned in July, after he was summoned for questioning about crimes against ethnic Serbs during and after the 1998-99 war, in which he served as an officer in the Kosovo Liberation Army. His departure triggered an early election, held in October.
Since then, Kosovo has been without a government, hindering the resumption of any progress on negotiations. In a call last week to Kosovo’s president, Hashim Thaci, Mr. Borrell stressed the need for a new government to be in place for negotiations to be able to proceed. Mr. Borrell also spoke by telephone with Aleksandar Vucic, the president of Serbia.
On Monday, Mr. Thaci nominated Albin Kurti of the nationalist Vetevendosje, or Self Determination, party as prime minister, three months after the election failed to deliver a majority.
The agreement on flights was signed by Milun Trivunac, state secretary of Serbia’s Ministry of Economy; Eset Berisha, director general of the Civil Aviation Authority of Kosovo; and Michael Knitter, the chief operating officer of Eurowings, a budget carrier owned by Lufthansa.
Following the signing at the American embassy in Berlin, Mr. Knitter said that flights would begin after both countries removed regulatory hurdles. It takes only 25 minutes to fly between Belgrade and Pristina, compared with more than five hours by road, including going through a border check, he said.
Eurowings has a plane and a crew stationed in Pristina and already flies from there to several destinations in Germany and Austria. Lufthansa flies in and out of Belgrade.
There was no schedule set for when flights might resume, Mr. Knitter said.