President Obama tried to defuse arguments for military action in a phone call last month with Prime Minister Benjamin Netanyahu of Israel, the substance of which was confirmed by an Obama administration official who spoke only on the condition of anonymity because he was not authorized to describe the conversation. While the two men have had an often contentious relationship over Middle East diplomacy, American officials emerged from that exchange persuaded that Mr. Netanyahu was willing to give economic sanctions and other steps time to work…

The Israelis have zeroed in on Iran’s plan to put much of its uranium enrichment near the holy city of Qum in an underground facility beneath so many layers of granite that even the Pentagon acknowledges it would be out of the reach of its best bunker-busting bombs. Once enrichment activities are under way at Qum, the Israelis argue, Iran could throw out United Nations inspectors and produce bomb-grade fuel without fear the facility would be destroyed.

At its core, the official said, the argument the Israelis make is that once the Iranians get an “impregnable breakout capability” — that is, a place that is protected from a military strike — “it makes no difference whether it will take Iran six months or a year or five years” to fabricate a nuclear weapon, he said.

The Americans have a very different view, according to a second senior official who has discussed the concept with Israelis. He said “there are many other options” to slow Iran’s march to a completed weapon, like shutting off Iran’s oil revenues, taking out facilities that supply centrifuge parts or singling out installations where the Iranians would turn the fuel into a weapon.