Israel, not Isreal.
Technically Iran has already attacked Israel, via proxies in Lebanon and the Gaza strip.
As for going for a direct attack instead of using proxies...sometimes even a regime which presents a disturbing religious philosophy and policies can practice reasonable political decisions for their own survival. but at the same time perhaps we should know better. in the early 90's Saddam's Iraq did bomb Israeli cities with long range missiles, so its not as easy to say its a far fetched scenario, especially in the face of the rhetoric coming from the Iranian leadership.
The timing of revealing the new nuclear facility and the successful launch of the Shahab 3 are not encouraging either.
as for the US standing by, I think an American decision needs to come from a realization that the improvements in the Iranian arsenal puts American forces under the range of this arsenal. the US needs to decide how far can it let an Iranian hegemony which will effect the American forces and alter the Middle East build up in the region. the most important analysis should be what are the points that the US is trying to achieve through diplomacy and playing the carrot and the stick game, and is achieving these points viable.
I'm not saying the only alternative is a physical assault on Iran, but a change in politics and diplomacy may be constructive. in a way it seems that the Iranian leadership looks at the world at the moment, and is not impressed by the opposition to its policies and its aspirations.
about an Israeli attack on Iranian facilities. already a long time ago I saw how that lost its momentum, with every passing year more complications appeared.