It isn't unprecedented. They did the same thing to Hussein decades back. Iran is like North Korea. They are balance precariously, banking on the fact we just don't want to go to the trouble and expense of mashing them to a pulp.
If they attack Israel, we will. Even if Isreal blows up their reactor, we will take their side. Iran simply can't deal with it. Sure, we are stretched way too thin for a ground assault, but honestly, unless you are overly concerned with collateral damage, what's the point in ground assault.
I hope there is no war with Iran. I hope Isreal doesn't need to blow up the reactor. I don't believe for a second, though, that Iran has a chance in hell of limping away if they retaliate.