If America can sell weapon systems to Saudi Arabia and still be Israel's "friend" why can't Russia sell the same to Syria?
I don't think Russia's subsidizing Israel to the tune of $3 billion a year. Plus, unlike Syria, Saudi Arabia doesn't have any territorial (or other major outstanding) disputes with Israel, and anti-Israeli terrorists don't use Saudi territory as a base for their activites, at least not at all to the same extent that Hezbollah and PFLP use Syria.
That said, I do find our relationship with the Saudis to be rather disquieting.