Former Israeli Defense Forces chief Dan Halutz said that Israel does not know where all Iranian nuke sites are located. Halutz, architect of Israel's disastrous failure (along with ex-PM Ehud Olmert) to finish of Hezbollah in the 2006 Israeli-Hezbollah war, likely is right this time. Halutz, unsurprisingly, does not want Israel to take the lead in confronting Iran.
The plain reality is that gleaning accurate timely intel about what goes on inside dictatorships requires a mole placed high inside the country's governing, military or intelligence structures. Western powers rarely can do this. If Israel has managed it, so much the better. We likely have not. Which is why our intel services almost certainly have no good idea as to where Iran is in its march towards The Bomb.
Bottom Line. Put simply, we must decide what to do with far less info than we wish to possess. Placing faith in our intel, after the debacle in Iraq & given a long history of unpleasant intel surprises on nuclear powers--e.g., North Korea in 2002 (announcement) & 2006 (actual test) there is no reason to think we know enough to cut it close as to when to take decisive action.
Letter from the Capitol, LFTC, National Security, Nuclear Proliferation, Arms
Control, WMD, Foreign Policy