Looking for His glorious appearing! Titus 2:13

The postcard from the Home Front Command that recently arrived in my mailbox looks like an ad from the Ministry of Tourism. A map of Israel is divided by color into six regions, each symbolized by an upbeat drawing: a smiling camel in the Negev desert, a skier in the Golan Heights.

In fact, each region signifies the amount of time residents will have to seek shelter from an impending missile attack. If you live along the Gaza border, you have 15 seconds after the siren sounds. Jerusalemites get a full three minutes. But as the regions move farther north, the time drops again, until finally, along the Lebanese and Syrian borders, the color red designates "immediate entry into a shelter." In other words, if you're not already inside a shelter don't bother looking for one.

The invisible but all-pervasive presence on that cheerful map of existential dread is Iran. If Israel were to launch a pre-emptive strike against Iranian nuclear facilities, Tehran's two terrorist allies on our borders—Hezbollah and Hamas—would almost certainly renew attacks against the Israeli home front. And Tel Aviv would be hit by Iranian long-range missiles.

On the other hand, if Israel refrains from attacking Iran and international efforts to stop its nuclearization fail, the results along our border would likely be even more catastrophic. Hezbollah and Hamas would be emboldened politically and psychologically. The threat of a nuclear attack on Tel Aviv would become a permanent part of Israeli reality. This would do incalculable damage to Israel's sense of security.

Given these dreadful options, one might assume that the Israeli public would respond with relief to reports that Iran is now considering the International Atomic Energy Agency's proposal to transfer 70% of its known, low-enriched uranium to Russia for treatment that would seriously reduce its potential for military application. In fact, Israelis from the right and the left have reacted with heightened anxiety. "Kosher Uranium," read the mocking headline of Israel's largest daily, Yediot Aharonot. Media commentators noted that easing world pressure on Iran will simply enable it to cheat more easily. If Iranian leaders are prepared to sign an agreement, Israelis argue, that's because they know something the rest of us don't.

In the last few years, Israelis have been asking themselves two questions with increasing urgency: Should we attack Iran if all other options fail? And can we inflict sufficient damage to justify the consequences?

As sanctions efforts faltered, most Israelis came to answer the first question affirmatively. A key moment in coalescing that resolve occurred in December 2006, when the Iranian regime sponsored an "International Conference to Review the Global Vision of the Holocaust," a two day meeting of Holocaust deniers. For Israelis, that event ended the debate over whether a nuclear Iran could be deterred by the threat of counter-force. A regime that assembles the world's crackpots to deny the most documented atrocity in history—at the very moment it is trying to fend off sanctions and convince the international community of its sanity—may well be immune to rational self-interest.

Opinion here has been divided about the ability of an Israeli strike to significantly delay Iran's nuclear program. But Israelis have dealt with their doubts by resurrecting a phrase from the country's early years: Ein breira, there's no choice. Besides, as one leading Israeli security official who has been involved in the Iranian issue for many years put it to me, "Technical problems have technical solutions." Israelis tend to trust their strategic planners to find those solutions.

In the past few months, Israelis have begun asking themselves a new question: Has the Obama administration's engagement with Iran effectively ended the possibility of a military strike?

Few Israelis took seriously the recent call by former U.S. National Security Adviser Zbigniew Brzezinski to shoot down Israeli planes if they take off for Iran. But American attempts to reassure the Israeli public of its commitment to Israel's security have largely backfired. Secretary of State Hillary Clinton's recent threat to "obliterate" Iran if it launched a nuclear attack against Israel only reinforced Israeli fears that the U.S. would prefer to contain a nuclear Iran rather than pre-empt it militarily.

On the face of it, this is not May 1967. There is not the same sense of impending catastrophe that held the Israeli public in the weeks before the Six Day War. Israelis are preoccupied with the fate of Gilad Shalit (the kidnapped Israeli soldier held by Hamas), with the country's faltering relations with Turkey, with the U.N.'s denial of Israel's right to defend itself, and with an unprecedented rise in violent crime.

But the Iranian threat has seeped into daily life as a constant, if barely conscious anxiety. It emerges at unexpected moments, as black humor or an incongruous aside in casual conversation. "I think we're going to attack soon," a friend said to me over Sabbath dinner, as we talked about our children going off to the army and to India.

Now, with the possibility of a deal with Iran, Israelis realize that a military confrontation will almost certainly be deferred. Still, the threat remains.

A recent cartoon in the newspaper Ma'ariv showed a drawing of a sukkah, the booth covered with palm branches that Jews build for the autumn festival of Tabernacles. A voice from inside the booth asked, "Will these palm branches protect us from Iranian missiles?"

Israelis still believe in their ability to protect themselves—and many believe too in the divine protection that is said to hover over the fragile booths. Both are expressions of faith from a people that fear they may once again face the unthinkable alone.