If Obama is a fence sitter as proven by his past actions and Iran is bluffing that they will strike back at Israel (if Syria is attacked) and if President Obama does what he says he will do, which is just fire a warning shot across Syria's bow ...
then what is to stop Iran from funding an air attack by missiles from who knows where, that will be blow to smithereens' by the dome in Israel's defense network and if these missiles contain harmful ingredients it will spread the harmful agent everywhere the debris fall.
Leaving a solid message to leave Russian/Iranian assets alone