You sound like an Albanian revisionist, how can Serbia invade itself?
Dogs can't use logic, they can only bark.
There were three other annexation attempts : in 1918, by the SHS Kingdom, in 1944 by Tito's Partisans, and in March 1989 by Milosevic and his red-brown gangs.
All were followed by extermination attempts, and all have ended in failure.
The Albanians are the natives in Kosovo, which is monoethnically Albanian.