Buried in this Jeffrey Goldberg report  on the state of U.S.-Israel relations is a somewhat encouraging piece of news:
This official agreed that Netanyahu is a “chickenshit” on matters related to the comatose peace process, but added that he’s also a “coward” on the issue of Iran’s nuclear threat. The official said that Obama administration no longer believes that Netanyahu would launch a preemptive strike on Iran’s nuclear facilities in order to keep the regime in Tehran from building an atomic arsenal [bold mine-DL]. “It’s too late for him to do anything. Two, three years ago, this was a possibility. But ultimately he couldn’t bring himself to pull the trigger. It was a combination of our pressure and his own unwillingness to do anything dramatic. Now it’s too late.”
Two years ago, Daniel Levy made  the case that Netanyahu was too risk-averse as a politician to do anything as hazardous and potentially disastrous as starting a war with Iran. That seemed very plausible  at the time, and I still find it persuasive. It has never  made  much  sense  that  the Israeli government would launch an attack  on Iran’s nuclear facilities. Even if Netanyahu were inclined to do this, which he reportedly isn’t, starting a preventive war against Iran wouldn’t prevent Iran from acquiring nuclear weapons.
On the contrary, a foreign attack would probably make the acquisition of such weapons a priority for the Iranian government. Especially if one believes the worst about the Iranian government’s intentions, it would be the height of folly to take action that would practically guarantee that Iran gets a nuclear arsenal, and that is what an Israeli or U.S. attack would do. The more important reason why such an attack didn’t make much sense is that it isn’t necessary for Israeli security. Even if Iran acquired nuclear weapons, Israel would have a much larger nuclear arsenal with which it would deter unconventional attacks. If Netanyahu is also risk-averse enough that he doesn’t want to take reckless military action against Iran, so much the better for all involved.