An Israeli strike on Iran's nuclear facilities would delay its manufacture of nuclear weapons by no more than two years, according to the prevailing assessment.

This assessment holds that Iran's nuclear program would technically be set back by only a year. But it would likely take Iran another year on top of that to overcome side effects of the strike that would cause additional delays.

The gap between Israel's military capabilities and those of the United States, as well as the gap between the countries' positions on the Iranian issue, were the focus of U.S. Defense Secretary Leon Panetta's visit here this week. But even though Israeli leaders have insisted, both publicly and privately, that an attack on Iran is necessary, it seems that two factors are reducing the likelihood of an Israeli strike before the U.S. presidential election in November.

The first is the administration's vehement opposition to such a strike at this time, in part because it might hurt President Barack Obama's reelection bid by sending oil prices higher. The other is the opposition of Israel's defense establishment: The top brass in both the Israel Defense Forces and the Mossad advise against attacking Iran before the elections, mainly out of fear that it would damage Israel's strategic relationship with the United States.

Supporters of an attack - mainly Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak - fear that opponents are adopting a policy of "it's too soon, it's too soon ... oops, it's too late." Or in other words, that the effort to postpone a strike by another three months is really meant to delay it until Israel can no longer attack at all. Once that happens, they fear, the international community would move to a policy of containing Iran - the very policy Obama promised not to adopt in his speech to the AIPAC conference in March.

Netanyahu and Barak argue that the longer a strike is delayed, the less effective it will be in delaying Iran's attainment of nuclear capability. Even now, some of what could have been achieved two years ago has become harder or even impossible, and if Israel waits too long, an attack would no longer accomplish anything.

The Americans counter that if necessary, they can wage an incomparably more effective attack - but it isn't necessary yet. And in any case, the prevailing assessment is that an Israeli strike would set Iran's nuclear program back by a year or two at most.

There are, of course, some who think Netanyahu and Barak are merely waging psychological warfare - by repeatedly threatening to attack, they are spurring Europe and America to ratchet up sanctions on Iran, which in turn might drive the ayatollahs to accept a compromise that would restrain their nuclear development. Moreover, this theory goes, the focus on Iran frees Israel from international pressure over the Palestinian issue, while also diverting Israelis' attention from economic and social grievances.

This theory can't be rejected out of hand. Barak, in particular, is tough to decipher. As the late Finance Minister Simcha Erlich once told an interviewer, "I don't say what I mean and I don't mean what I say." It's often hard to follow the logic of Barak's moves in the strategic billiards game he is playing on behalf of all of us.

But on the other hand, Barak has never been as clear and resolute as he now seems to be on the Iranian issue. He speaks as if out of a deep inner conviction.

Moreover, historic examples of other prime ministers, from David Ben-Gurion to Menachem Begin, are being trotted out regularly, and the message is clear: Only far-sighted leaders understand the magnitude of the danger and act accordingly, despite the obstacles put in their way by short-sighted colleagues. After all, Barak claims, experts also expected the Israeli strike on Iraq's nuclear reactor in 1981 to set that country's nuclear development back by only two years, but in the end, Iraq never managed to rebuild its nuclear weapons program.

And third, most defense professionals believe Netanyahu and Barak are serious - as do many in the media.

Yesterday, this debate even made the front page of The New York Times: The paper quoted former Mossad chief Efraim Halevy saying that if he were an Iranian, he'd be "very fearful of the next 12 weeks," but also quoted Obama administration officials saying they believe Israel will accede to American urgings to delay an attack until at least early next year.

The trouble, however, is that this entire drama is also being watched by the Iranians. And based on the hard line they have taken in their negotiations with the Western powers over the last few months, in which they have not retreated by so much as a millimeter or displayed any willingness to compromise, it seems that Tehran, at least, doesn't believe Israel will attack in the next few months.