See my other reply. In any case, that you can refer to these as ‘aggressive imperialist power plays’ shows you’re both not to be taken seriously and are not willing to engage in a good faith and informed discussion.
The Serbian campaign was ethnic cleansing on a massive scale, forcefully and methodically expelling over a million Kosovar Albanians from the area by the time they were stopped by NATO’s intervention. That does, arguably, rise to the level of genocide under the standard definitions.
Just because someone can claim something doesn’t mean it’s right. That determination is up to independent observers, experts, and courts, and tribunals.
Russia tried to claim at the ICJ that it was invading Ukraine under the Genocide Convention. The court ruled that it had to end to the invasion immediately, which Russia ignored.
That wasn't defensive by any means, but that also doesn't make it unjustified nor should it really be called "aggressive".
Chomsky, naturally, denied that ethnic cleansing was happening there because it wasn't the US or "western" countries doing it.