There is further evidence they are working on a nuclear weapon.
At what point does Israel pull the trigger on Iran?
My best guess, soon. Not soon like next week or next month, but soon as in within 2 to 5 years. I believe Israel is building up its anti-ballistic missile defenses. Remember, they are within range of Iranian missiles now. I believe that as soon as Israel's military and civilian leadership is confident that they can counter any ballistic missile threat from Iran, they will go.
Consider, everyone knows it is Iran pulling the strings on Hezbollah and Hamas and calling the shots over there. Iran and the whack-job leading them want Israel wiped off the map, literally. He has said exactly that. Iran has a pretty good missile program, witness their recent test firings. Who else is in range of these missiles, and an enemy of Iran? Add to that Iran is working on a nuclear program.
So Israel knows Iran is coming for them, it is just a matter of time. Right now they have relatively few missiles capable of hitting Israel. It is basically an arms race, Israel trying to put a defense in place more quickly than Iran builds up its delivery vehicle program, and its nuclear program. As soon as Israel has a clear lead, they are going to strike. They would be fools not to, and when it comes to defense, Israel makes very few foolish moves. They need to strike before Iran can deliver nuclear weapons. Better to strike earlier, before the devices are weaponized and loaded on the missiles. With existing ABM technology and systems they have a high probability of knocking down most if not all the incoming warheads. Better to ride out a few HE systems now, rather than NBC weapons later. I think Israel is just buying/developing the last pieces, and putting the finishing touches on their CONOPS for missile defense, then it is Iran's turn in their sights.
Finally, consider what I read here a couple of days ago - apparently Israel asked for permission to overfly Iraq on their way to Iran and were told no. Well, as soon as O pulls the US out of Iraq (assuming he actually becomes President in spite of his apparent ineligibility), the native Iraqi air force won't be able to stop them, and Israel will have their best route available. So in that regard, the sooner O pulls us out of Iraq, the sooner Israel gets its green light.