A couple of years ago, Vice President Joe Biden, on a visit to Israel, offered Prime Minister Benjamin Netanyahu a piece of advice. He shared something his father often said: “There’s no sense dying on a small cross.”

Few American politicians would think it wise to invoke crucifixion in a conversation with the leader of the Jewish state (though the Jerusalem setting was apt), and fewer still would get away with it. But Netanyahu, who considers Biden his closest friend in the Obama administration, laughed. What he didn’t do was take the advice in the way it was intended.

What Biden meant was for Netanyahu to quit offering partial and ephemeral freezes in West Bank settlement-building, and to try instead for a dramatic compromise with the Palestinians, even if he had to pay a very high political price.

Instead, Netanyahu applied Biden’s aphorism to a different issue facing his country: what to do about Iran’s nuclear ambitions. Netanyahu has been warning about Iran’s nuclear program since the 1990s; now, as prime minister, he is in a position to do something about it. The lesson he took from Biden is that Iran is the one issue important enough to risk everything for.

Dangerous Overconfidence

There are a few reasons why this episode is now so important. Last week, I wrote about some of the assumptions Israel’s leaders are making about the potential fallout from a strike on Iran’s nuclear sites. I visited Tel Aviv and Jerusalem this month, and I was struck, in my conversations with Israeli officials and ex-officials, by the number of best-case scenarios they offered up. They seemed dangerously overconfident that they could manage the aftermath of a strike, and this has led them to contemplate what seems to me -- at this moment at least -- a precipitous and premature attack.

I also went to Israel to test a notion I’ve often heard: that Netanyahu might be engaged in an enormous bluff. I doubted this theory (and certainly President Barack Obama and his secretary of defense, Leon Panetta, doubt it). But it seemed worth testing, in part because Netanyahu’s campaign to focus the world’s attention on Iran has worked so well without his having to resort to military force.

I came away from this visit certain that Netanyahu isn’t bluffing. I disagree with Panetta’s view that an Israeli attack could come by June, but I do think that, if current conditions prevail, there is a very good chance Israel will strike by the end of the year.

Which brings me to another belief of the Israeli leadership I heard during my visit. This one might surprise Obama’s critics among right-wing Israel supporters (and among Republican presidential candidates): The Israelis don’t see Obama as an adversary. Especially after the air-clearing meeting between Obama and Netanyahu this month at the White House, the Israeli leadership is fairly confident Obama will side with them if they launch an attack, and they are also fairly confident the president is serious when he suggests that the U.S. might one day use force to stop Iran.

But that’s almost beside the point. From the perspective of the two men who matter most in the Israeli decision-making process -- Netanyahu and Defense Minister Ehud Barak -- American promises are somewhat immaterial. Because it is imprinted on the Israeli DNA that Jews, post-Holocaust, shouldn’t rely on the kindness of non-Jews to bail them out of trouble. In other words, no matter how strong Obama’s rhetoric, Israel’s leaders will not subcontract out their defense to the U.S. or any other party.

Question of Timing

Senior officials I met with also told me that there are no gaps between the U.S. and Israel on intelligence issues, or in a basic understanding of the Iranian threat. The only gap is in timing: U.S. officials are confident they could destroy Iran’s nuclear facilities in 2013 or 2014 if they needed to. The Israelis seem to believe that, because of their more modest offensive capabilities, they either strike in 2012 or don’t strike at all.

In fact, I’ve concluded that there are only two reasons Israel’s leaders haven’t struck already.

First, they believe that there is still some time before Iran enters the “zone of immunity,” in which its nuclear sites are so hardened or spread so widely that a strike would be ineffective. And second, because Iran has not yet approached the zone of immunity, Israeli leaders believe they can still pay heed to Obama’s request to hold off. (Ultimately, they will make their own decision about a strike, but they believe they should heed the wishes of Israel’s most important ally while they can.)

When Israeli leaders conclude that Iran has reached the threshold of the zone of immunity, there’s a strong likelihood they will act.

Which brings us back to Biden’s cross. Netanyahu is a cautious man, who seems mainly interested in preserving his ruling coalition. But Netanyahu’s father, Benzion Netanyahu, a renowned scholar of the Spanish Inquisition, taught his sons that the Jewish people are constantly threatened by extinction-level plots, and the prime minister has internalized this understanding of Jewish history.

Another family story may have even more salience: the martyrdom of Netanyahu’s brother, Yonatan, during a 1976 operation to free Israeli hostages in Uganda. Yonatan died in the act of rescuing Jews. His brother understands that whatever hardship he experiences by taking action against Iran, the price he pays will not be the price his brother paid in pursuit of what he sees as the same goal: protecting Jews.

In other words, Iran’s nuclear program, to Netanyahu, is Biden’s very large cross.

(Jeffrey Goldberg is a Bloomberg View columnist and a national correspondent for the Atlantic. The opinions expressed are his own.)

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To contact the author of this column: Jeffrey Goldberg at goldberg.atlantic@gmail.com.

To contact the editor responsible for this column: Timothy Lavin at tlavin1@bloomberg.net.