Trade unions in Kosovo threatened on Friday to go out on strike after the impoverished Balkan country's new prime minister vetoed annual 25-percent public sector pay hikes promised by his predecessor. Prime Minister Isa Mustafa told Reuters on Thursday a promise by his predecessor Hashim Thaci to raise wages by 25 percent per year over the next four years would be "impossible" to keep, but that they would rise in line with economic growth. "You have started running the country very badly, Prime Minister Mustafa," the head of Kosovo's union of teachers, Rrahman Jasharaj, wrote in a public lett