Here are two headlines from today: 'US-Israel divisions over Iran boil over' (AP); 'U.S.-Israel tensions on Iran are boiling over' ( JTA). This may lead you to ask (if you're the type who likes to keep metaphors intact), "What is the underlying source of heat?"
This question can be broken down into five sub-questions:
 Is it true, as Bibi Netanyahu says, that the point of contention is the unwillingness of the U.S. to set a "red line"--i.e., a line that, if crossed by Iran, would bring U.S. military action?
Not really. Obama has already laid down a red line. He did so pretty clearly on this very web site, in an interview with Jeffrey Goldberg in March: "As president of the United States, I don't bluff... I think both the Iranian and the Israeli governments recognize that when the United States says it is unacceptable for Iran to have a nuclear weapon, we mean what we say." In other words, if Iran tries to build a nuclear weapon--something that would require, for starters, the very conspicuous breaking of UN monitoring seals at its nuclear facilities--Obama will resort to military force to stop it.
 Well then what is the real disagreement between Obama and Netanyahu?
Netanyahu would like Obama to move the red line. He thinks Iran shouldn't even be allowed to have a "nuclear weapons capability"--i.e., to be in a position where, if it decided to build a bomb, it could do so in, say, six months or nine months or ... well, the number of months can vary, depending on who is defining "capability." That's why "capability" is such a vague red line (more like a red blur, really). By the more expansive definitions, Iran already has weapons "capability," because it could probably build a crude (though not "deliverable") bomb within a year.
 If the US has in fact established a red line, why are people reporting that it hasn't?
Some journalists are just taking Netanyahu's word for it. But the misunderstanding has gotten an assist from the Obama administration. Earlier this week, State Department spokesperson Victoria Nuland, in what presumably was an inadvertent misstatement, said , "It is not useful to be parsing it, to be setting deadlines one way or the other, red lines." Her boss, Hillary Clinton, had simply said, "We're not setting deadlines," and I think that was the intended formulation.
 Deadlines? What's this about deadlines--and what's with all the "red lines, deadlines" wordplay in headlines?
Apparently Netanyahu would like Obama to set some deadline after which Iran would be bombed if negotiations hadn't succeeded in getting it to stop enriching uranium. But this is really just another way of saying that Netanyahu wants Obama to move the red line from trying to build an actual nuclear weapon to having a nuclear weapons capability. After all, if Iran ended its enrichment, it wouldn't have a "capability." (Enrichment is permitted under the Nuclear Nonproliferation Treaty, and has legitimate civilian uses, though the UN Security Council has demanded that Iran suspend enrichment. Hillary Clinton has said the international community could in the long run live with an Iran that enriches uranium, so long as UN monitoring was tight.)
 So where is this headed?
Hard to say. Netanyahu has in the eyes of some analysts declared war on Obama; he seems to be trying to damage Obama's re-election chances by planting doubts about his pro-Israel credentials in the minds of Jewish and right-wing evangelical voters. As I write this, there are reportsthat Obama has responded in kind, denying Netanyahu's request for a meeting when Bibi comes to New York later this month for the UN General Assembly meeting. But there are also reports that Netanyahu didn't even make such a request. It's all very fluid at the moment. In any event, I suspect that, if Obama wins re-election, this tension between the two men will only increase the chances that he then moves quickly toward what may well be a gettable deal with Iran: Iran is allowed to enrich uranium (possibly after a period of suspended enrichment) and accepts very intrusive monitoring of its program to make sure it doesn't approach weaponization. If such a deal happens, will Netanyahu be happy with it? Maybe not, but I don't think Netanyahu's psychological well being will at that point rank high among Obama's concerns.