In a country of hard men, Meir Dagan, the recently retired head of the Mossad, Israel’s foreign intelligence service, is one of the hardest. He is the Siberian-born son of Holocaust survivors, an ex-commando who has arranged the assassinations of many of Israel’s enemies.

He is devoted to the defense of his country, and, like most of Israel’s samurai class, sees Iran, and its Jew-hating, missile-obsessed leadership, as his country’s foremost threat, because of its nuclear intentions and its support for the Islamist terror groups that seek Israel’s destruction.

So a pressing question in Israel today is this: Why has Dagan called into question the wisdom ― and, privately, even the sanity ― of any Israeli leader who contemplates a preemptive strike on Iran’s nuclear facilities?

The answer illuminates an enormous divide within Israel’s national-security establishment. It also suggests that Dagan, without peer as a saboteur, assassin and spy, is a bungling strategist.

In two recent speeches, Dagan called an Iran strike “a stupid idea,” and said “the regional challenge that Israel would face would be impossible.” He has made clear he believes that Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak are driving Israel toward a war it can’t win. He has said that while in office he worked with other security officials to thwart “any dangerous adventure.” But, he went on, “Now I am afraid that there is no one to stop Bibi and Barak.”

Last year, while reporting on the possibility of an Iranian-Israeli confrontation ― the world’s most serious latent crisis ― I heard repeatedly from officials familiar with the Mossad’s views that the agency thought the costs of an Israeli strike on Iran would outweigh the benefits. The Mossad analysis held that such an attack would not be an echo of the 1981 Israeli bombing of Iraq’s Osirak nuclear reactor, because Iraq had concentrated its nuclear program in one place.

Iran’s nuclear program is spread throughout the country, and Iran, of course, is farther from Israel. Mossad analysts are also certain that Iran would order its Hezbollah proxies in Lebanon to launch thousands of rockets at Israel. This could force the Israeli air force to break off its attack on Iran in order to defend Israel in what could be a multifront assault.

Even so, the Mossad, like every agency in Israel’s national security establishment, views Iran’s nuclear program as a threat to Israel’s existence and understands that the mere possibility of an Israeli attack helps deter Iran’s ambitions.

So what caused Dagan’s break with his former boss, and his decision to publicly undermine Netanyahu’s position that, in the now-familiar phrase, “all options are on the table”?

I spoke with several people familiar with Dagan’s thinking. They told me he believes that Barak, in particular, sees no great downside to a strike on Iran, and that Netanyahu is a prisoner to the idea that it’s his personal responsibility to stop a potential new Holocaust. They also suggested that Netanyahu wants to change the subject from his difficulties with the Palestinians.

It’s no secret that the prime minister has been outfoxed by the Palestinian leadership lately, and that Israel is desperately trying to stop a Palestinian independence initiative at the United Nations. Netanyahu is capable of great cynicism, and he has made clear that the peace process doesn’t interest him very much. But launching an airstrike on the Persian Empire? He would do such a thing only if he believed Israel’s existence was in danger, and that the U.S. was prepared to stand by as Iran went nuclear.

Today, there’s a war within the Israeli defense establishment, a war of competing analysis. Dagan leads the camp of officials and ex-officials who believe that Netanyahu should spend all his time trying to convince President Barack Obama that only the U.S. is capable of neutralizing the Iranian threat, and that Netanyahu should shelve the idea, once and for all, of launching an attack himself.

There is much to credit in Dagan’s argument. Iran may be too large a problem for a small state to handle, even a small state with a potent air force. And he is certainly correct to say that Netanyahu and Barak, the only two men with the power to order a strike, are seriously contemplating military action. Dagan would not have spoken out in such dramatic fashion, and burned so many bridges, if he thought Netanyahu and Barak weren’t serious.

But Dagan didn’t count on one thing: His public denunciations may actually bring Israel closer to launching an attack. He has undermined the credibility of Israel’s deterrent posture. Western intelligence agencies, the Obama administration and the International Atomic Energy Agency all suspect that Iran’s leaders are moving steadily toward a nuclear bomb, less fearful of an Israeli strike than they were last year. The Iranians, intelligence officials told me, believe Dagan’s statements reflect the position of Israel’s defense establishment.

They don’t. But this perception is critical. If Israel does attack the Iranian nuclear program, it will in part be because Dagan undermined his country’s deterrent credibility.

Lately, it has become received wisdom that Israel is leaning against a strike and is instead pinning its hopes on Obama. But those who argue that Netanyahu would not attack Iran know nothing about the man, about his fears, his militancy, his belief that history has entrusted him with the survival of the Jewish people. Meir Dagan might not know strategy. But he knows to take Netanyahu’s preoccupation with Iran seriously. 

By Jeffrey Goldberg

Jeffrey Goldberg, a national correspondent for The Atlantic, is a Bloomberg View columnist. The opinions expressed are his own. ― Ed.