My best guess is that there will be no attack, because unlike the precious destruction of nuclear facilities is Iraq and Syria, Iranian nuclear operations are scattered across hundreds of locations.
If open conflict were to happen, the Israeli's couldn't do it alone. If the US were to assist, the Russians may move a few units accross the ground but would not engage American units as it would not be in their interests to do so. The US would clearly need to engage some next generation weaponry to take down a few waves of Silkworm and Sunburn missiles seconds after lauch if fleet losses are to be avoided.
Strategically, US and Iranian interests largely align but neither side will admit this so the sabre rattling and hidden war continue.
