I don't think it's such as a big mystery. They are interested in a number of things: number one is money, in selling weapons to arabs; number two, is making life worse for US and it's allies. They obviously don't care that more than 1 mil of former Soviet Union citizens live now in Israel and that their lives may be in danger because of Russia misguided policies. What is most strange is that this policy going essentially against Russia's interest only. But, again, this will be in the future. Right now, what is most important, is make life miserable for US.
Western-backed Syrian rebels say kill foreign Islamic State (Reuters)
from the article: Russian FM says weapons sales to Syria strictly controlled