Your source.
Russia was our friend and ally in the procurement of weapons in the early 1990s. The Russians supplied us with weapons at the request of France. I am a witness to that - says Marin Tomulić in the conversation we had on Wednesday in Paris. - Now it is considered that the Russians were and remain allies of the Serbs. But during the Homeland War, they armed us, not the Serbs - he adds.
Your source states that Russia sent or sold weapons at the request of France - let's say that is accepted. But, you are ignoring the direct intervention of USA in the conflict in 1999. It was not until this intervention ramped up that the war had a end in sight.
https://en.wikipedia.org/wiki/Yugoslav_Wars#TimelineI can see you are looking at only the half of the story - the one that reinforces your views.