Iran has positioned mobile short range ballistic missiles in Syria. These missiles if launched would strike Israeli targets in less than forty seconds. They would be virtually impossible to stop. If Israel does attack Iran, it will face a devastating counterattack. An Israeli solo attack is not likely to be successful, and may result in severe damage and many casualties in Israel. Obama has made it clear he has absolutely no intentions of joining an Israeli attack on Iran. Netanyahu is facing a very difficult strategic reality.
Are Iranian rockets safe inside Syria with the civil war ongoing? Which regions are they in?
With Saudi Arabia becoming more and more agitated, I can actually see them facilitating an Israeli airstrike which they were loathed to do before, but a joint offensive by the Saudis and Israel could go bad very quickly, especially since (thanks to OBungle) Iraq is now a Shiite client state. Iran has the 8th largest military in the world, when you factor in paramilitary assets and reserves. Surprisingly, they lead even the USA in this regard. Even when it comes to simply the standing army, they remain in 8th place.
If Iran launched an invasion of the Arabian peninsula in order to cut off Israel’s ability to strike from the air due to the long distances required going around the peninsula, they would be in real trouble. My guess is it would come down to how badly Hezbollah could damage the Israeli military before they controlled Lebanon. If they prove to be a potent threat, Israel could run out of time as Iran closes in.