I can't recommend this Jeff Goldberg article in The Atlantic highly enough. After several years of interviews with leaders and policy makers from Israel, Iran, America, and other Arab countries, as well as talks with military experts, Goldberg comes to this reluctant conclusion:

I have asked a simple question: what is the percentage chance that Israel will attack the Iranian nuclear program in the near future? Not everyone would answer this question, but a consensus emerged that there is a better than 50 percent chance that Israel will launch a strike by next July. (Of course, it is in the Israeli interest to let it be known that the country is considering military action, if for no other reason than to concentrate the attention of the Obama administration. But I tested the consensus by speaking to multiple sources both in and out of government, and of different political parties. Citing the extraordinary sensitivity of the subject, most spoke only reluctantly, and on condition of anonymity. They were not part of some public-relations campaign.) The reasoning offered by Israeli decision makers was uncomplicated: Iran is, at most, one to three years away from having a breakout nuclear capability (often understood to be the capacity to assemble more than one missile-ready nuclear device within about three months of deciding to do so). The Iranian regime, by its own statements and actions, has made itself Israel's most zealous foe; and the most crucial component of Israeli national-security doctrine, a tenet that dates back to the 1960s, when Israel developed its own nuclear capability as a response to the Jewish experience during the Holocaust, is that no regional adversary should be allowed to achieve nuclear parity with the reborn and still-besieged Jewish state.

When the Israelis begin to bomb the uranium-enrichment facility at Natanz, the formerly secret enrichment site at Qom, the nuclear-research center at Esfahan, and possibly even the Bushehr reactor, along with the other main sites of the Iranian nuclear program, a short while after they depart en masse from their bases across Israel-regardless of whether they succeed in destroying Iran's centrifuges and warhead and missile plants, or whether they fail miserably to even make a dent in Iran's nuclear program-they stand a good chance of changing the Middle East forever; of sparking lethal reprisals, and even a full-blown regional war that could lead to the deaths of thousands of Israelis and Iranians, and possibly Arabs and Americans as well; of creating a crisis for Barack Obama that will dwarf Afghanistan in significance and complexity; of rupturing relations between Jerusalem and Washington, which is Israel's only meaningful ally; of inadvertently solidifying the somewhat tenuous rule of the mullahs in Tehran; of causing the price of oil to spike to cataclysmic highs, launching the world economy into a period of turbulence not experienced since the autumn of 2008, or possibly since the oil shock of 1973; of placing communities across the Jewish diaspora in mortal danger, by making them targets of Iranian-sponsored terror attacks, as they have been in the past, in a limited though already lethal way; and of accelerating Israel's conversion from a once-admired refuge for a persecuted people into a leper among nations.