An Attack on Syria is an Attack on Iran
Recenly, Ali Akbar Velayati, a close adviser to Iranian leader Ayatollah Ali Khamenei, issued a warning that an attack on Syria would be tantamount to an attack on Iran. While it may or may not be hollow threat, it does throw caution to the US or more likely, Israel, about any plans about intervening in Syria. An Israeli attack on Syrian rebels armed with chemical weapons would serve Tehran’s purpose in getting all of the groups involved to fight their common enemy-Israel. It would unite them in many ways. It would also negate any Israeli plans for attacking Iran's nuclear facilities.
US intelligence strongly suspects that some of the Syrian chemical arsenal have already reached Hezbollah and are stashed away in fortified bunkers in the Beqaa Valley, Lebanon, strongholds, along with some long- and medium-range ground-to-ground rockets smuggled secretly across the Syrian border. This is not a shocker. The valley has long been in Syrian control since the 1980's. If Israel were to attack there, the same problem would occur since Hezbollah is heavily tied to Iran and Syria.
Israel is becoming increasingly paranoid about the storm clouds surrounding them: Syria to the east, Lebanon to the north, and Egypt being unable to control the vast Sinai area where weapons are smuggled from Iran. So, they have deployed the the Iron Dome missile defense system near the Syrian border and are building a 57 km fence along it.
Iran could engage with Israel indirectly through Syria or more likely, Lebanon. They could distract the attention of Israel from attacking Iran, solidify groups against a common enemy and stall nuclear talks to buy more time to get their bomb and rockets capable of carrying it. These "skirmishes" would embroil Israel from many sides.
Israel needs to be careful as to how and when to use its superior military force.