Serbian news is not reporting anything similar. This is not the first time that air raid sirens have been herd in Northern Kosovo this year. No need to panic yet.
Serbian president just said they are going to win the war.
Keyword is if. Vučić loves saying inflammatory shit like this, it raises his popularity. He is a EU puppet, no chance that he will start anything.
Some of the recent tweets seem to indicate that the Kosovar army is planning to attack at midnight. Hopefully just a bluff.