As far as I can remember, Serbia started to expel Albanians from their home AFTER the bombing started. Some say the expulsions would have happenned anyway, that the bombing only triggered what was already prepared. Maybe they are right, but nobody knows for sure. The excuse for the NATO ultimatum and then bombing was the lack of respect for human rights the Serbian army employed in the fight against separatist guerrillas (some would rather call them terrorists). Particularly one massacre of about 40 persons had atracted much attention.
Key U.S. House Democrat cites troublesome issues in Iran nuclear deal (Reuters)
from the article: Netanyahu's on the way to Kosovo