Time to attack Iran? Obama-Netanyahu summit could make fateful decision.

President Obama greets Israeli Prime Minister Benjamin Netanyahu at the White House Monday for what are likely to be the most consequential talks the two leaders have had. The significance is because of the topic that will dominate their discussion: Iran.

The conversation could determine nothing less than whether there is a military strike on Iran’s nuclear facilities sometime before the US elections in November.

High-priority topics will include how much time to give the “crippling” sanctions that both the United States and Israel say they still hope can persuade Iran to change course on its nuclear ambitions; what to watch for in (and expect from) international talks with the Iranians, which are expected to resume in the next month or so; and each leader’s red lines that, once crossed, would trigger military action against Iranian nuclear facilities.

The Obama-Netanyahu relationship is actually less strained than conventional wisdom would suggest, some experts with close knowledge of the two leaders say.

The tensions between the two governments over Iran have little to do with personality, some say, and more to do with the differing assessments on each side of when Iran will have to be stopped militarily. Also, Israel, as America’s junior in terms of military might, is likely to feel a need to act sooner than the US does.

“There is a timeline issue,” says Dennis Ross, a longtime US Mideast diplomat who until recently was the Obama administration’s special envoy on the Middle East and Iran.

That timeline has “less to do with where the Iranian nuclear program is” and more to do with “the point at which Israel loses the ability to act militarily,” Mr. Ross says. Because of America’s more extensive military capabilities, “That zone of immunity [at which point Iran’s progress toward developing a nuclear weapon is beyond military setback] arrives earlier for them [the Israelis] than for us.”

Another difference is how the two governments perceive the Iranian threat. To Israel, a nuclear Iran would pose an existential threat, since some Iranian leaders have called for Israel’s annihilation and since Iran already possess missiles that can reach Israel.

For the Obama administration, the central threat of a nuclear Iran would be in how it would almost guarantee the advent of a nuclearized Middle East, which would dramatically increase the likelihood of a nuclear war.

Monday’s meeting takes place in a highly politicized context. Mr. Netanyahu will be in Washington to address the American Israel Public Affairs Committee, the pro-Israel group that Mr. Obama is to address Sunday. The annual AIPAC conference is always a high-profile affair, but this year the meeting’s eye-popping 14,000 attendees – normal attendance is closer to 9,000 – suggests both the high level of interest in the Iran issue and the fact that this is a presidential election year.

Three Republican presidential contenders – Mitt Romney, Rick Santorum, and Newt Gingrich – are scheduled to address the conference on Tuesday, either by satellite or video.

The Obama-Netanyahu meeting Monday follows a string of high-level meetings between US and Israeli administration and military officials. Five Republican senators were recently in Jerusalem, and at the conclusion of their meetings Sen. John McCain (R) of Arizona spoke of “significant tension” between the two governments over their assessments of the Iranian threat.

But Ross, who is now at the Washington Institute for Near Eastern Policy, says his recent experience in the administration suggests to him that there is more agreement between the two governments on how to proceed about Iran than some observers suggest.

“There is a basic commonality in terms of objectives, meaning Iran should not have nuclear weapons,” he says. “There is commonality in terms of preferred means, that this should still be done through diplomatic means if it can be done.” Finally, he says, there is agreement that “crippling sanctions are the way to affect Iran’s behavior.”

Some critics of Obama foreign policy fault the president for pressuring Israel early in his presidency to make concessions on settlements to reach peace with the Palestinians. Mr. Romney has accused Obama of “throwing Israel under the bus” by calling for a peace accord based on 1967 borders, and Mr. Santorum has used the same expression to describe what he calls the president’s willingness to abandon Israel in exchange for Mideast oil.

But Ross says the meetings he has witnessed between the two leaders have been “quite serious and thoughtful.” And he points to occasions when Netanyahu has called on Obama for assistance – as when Israeli employees were trapped in their embassy in Cairo last year during the anti-Mubarak uprising. He says, “That tells me ... there is actually a high degree of trust.”