Carl,

This AM on BBC Radio Four an Israeli commentator was asked about the arrival of the SAMs, his response was noteworthy; these are not his exact words:
Our concern is not over the arrival of the missiles, which may not be ready to use for sometime. It is whether they provide cover for our enemies to launch attacks and if should they fall into the hands of our enemies. Israel has taken a very clear stance on what is happening in Syria. We support no-one.
Given the internal situation such weapons - when ready - do not help the regime to win the civil war. Nor do they deter foreign or more accurately US intervention. What is their actual value is unclear. They may act as a visible sign within Syria that Russia remains a helpful friend; which I am sceptocal about.

Note Russia this week was reported as evacuating all Tajik nationals, after their government said leave.