"Snakes as you fully understand tend to slither through the grass to avoid being killed."
To carry your analogy out a bit, I'd claim that the best way to clear out the viper nest in the garden (or ME, in this case) is to set a mongoose or two to the task.
As the Hezzys/Syria just finished painfully learning (again), the number one mongoose in the ME is the IDF, as they have been for the last fifty years.
What Syria, Iran and the rest of the Islamofascists have to fear most right now is any continued involvement at all by the US in Iraq, hence their and their allies' continuing propaganda campaign to get us out.
First, the forces we have on the scene have shown themselves to be more than a match for any one of them or all of their combined military or paramilitary. As far as they are concerned, we have turned Iraq into one giant killing field, and have very thoroughly established ourselves as the Mother of All Mongooses in their snakey little world.
Far worse for them in the long term is the reconstruction of Iraq, especially after the role the Islamofascists have played in support of Saddam and the continued terror campaign against the Iraqi people since he was overthrown. The reconstituted Iraqi Army is still only in the mongoose kit stage, but isn't far from going out on the hunt and has absolutely no reason to love any of their murderous neighbors.
...Not to mention the daily problems that Iranian and Syrian "leaders" must encounter in merely keeping the lid on their own internal political opposition. With all the media fluff about their religious fatalism, all of 'em really, really like all those perks they've got and don't have any interest at all in becoming anything as permanent and stupid as dead.