GWEN IFILL: Amid growing nervousness about the prospect of an attack, Margaret Warner reports on the possible repercussions of strikes and counterstrikes between Israel and Iran.
MARGARET WARNER: Some 1,000 protesters marched in Tel Aviv last weekend, urging the Israeli government not to attack Iran's nuclear facilities. "Bibi, don't bomb Iran," the posters read, calling Israeli Prime Minister Benjamin Netanyahu by his nickname.
The protest reflected mounting concern among Israelis that their leaders may be on the verge of launching a preemptive strike against Iran's expanding nuclear program. Though the Iranian regime has vowed to destroy the Jewish state, recent polls in Israel show only 19 percent would support their government attacking Iran unilaterally.
Alarm is growing in Washington as well that an Israeli strike may be in the offing, with unpredictable consequences for the region and the United States.
PRESIDENT BARACK OBAMA: Already, there is too much loose talk of war.
MARGARET WARNER: To the American Israel Political Action Committee early this month, President Obama made a major commitment. He will prevent, not simply contain, a nuclear-armed Iran.
BENJAMIN NETANYAHU, Israeli prime minister: Thank you, too, for that strong speech yesterday.
MARGARET WARNER: But in a White House meeting the next day with Prime Minister Netanyahu, the president continued to argue for giving sanctions and diplomacy more time to work.
BARACK OBAMA: In my speech when I say all options are on the table, I mean it. Having said that, I know that both the prime minister and I prefer to resolve this diplomatically. We understand the costs of any military action.
MARGARET WARNER: Yet, that evening, Netanyahu told the AIPAC gathering that, as far as Israel is concerned, time is running out.
BENJAMIN NETANYAHU: My friends, Israel has waited, patiently waited for the international community to resolve this issue. We have waited for diplomacy to work. We have waited for sanctions to work. None of us can afford to wait much longer.
JEFFREY GOLDBERG, The Atlantic: I think it's highly plausible that Israel would decide to strike Iran's nuclear facilities some time this year.
MARGARET WARNER: Journalist Jeffrey Goldberg, who talks frequently with senior Israeli and U.S. officials, is national correspondent for The Atlantic. He says the two allies don't share the same timetable on when preemptive action might be called for because Israel doesn't have the military might that the U.S. does.
JEFFREY GOLDBERG: The Israelis believe they have a shorter window of opportunity. They believe that the Iranians are building redundancy into their systems, meaning, right now, you're talking about five or six or eight different nuclear sites. But, in another year, it's going to be 12 or 16 or 20.
The calculations are, there's going to come a point when we no longer can do this. This is what they tell me. We're not going to be able to do this in six or nine or 12 months. And then it's going to be up to the United States to deal with this issue. The Israelis don't want to subcontract out their existence or the guarantee of their existence to any country, even their best friend in the world, the United States of America.
MARGARET WARNER: The notion that Israel could attack Iran's nuclear facilities, as it did in Iraq three decades ago and Syria in 2007, is not new. But Israel's timeline acquired more urgency recently.
Austin Long is a defense analyst and assistant professor at Columbia University.
AUSTIN LONG, assistant professor, Columbia University: The Israelis have a really robust military capability to destroy the key parts of the Iranian nuclear facility or the nuclear program.
MARGARET WARNER: Those include the uranium enrichment site at Natanz and the processing plants at Isfahan. But there's a newer, harder-to- attack enrichment facility revealed in late 2009 that's buried under 300 feet of rock at Fordow, near the holy city of Qom.
AUSTIN LONG: This is an incredibly challenging target, much more challenging than Natanz or any of the other facilities.
MARGARET WARNER: To get at these facilities, the most direct route for Israeli warplanes would be due east across Jordan and Iraq. To most sites, Long said, Israel will likely deploy its modified F-16 jets carrying 2,000-pound bunker-buster bombs. To Fordow would go its F-15 jets carrying 5,000-, as well as 2,000-pound bombs.
But those bombs would have to hit with unprecedented precision.
AUSTIN LONG: It would require six or seven 5,000-pound bunker-busters sort of impacting one after another at the same spot. You would have opened essentially a crack or a tunnel down through 80, 90 meters of rock. The idea would be to have one bomb that finally went all the way through into the space where the centrifuges are and then exploded.
These are very accurate weapons, but getting seven bombs to sort of line up would require using many more than seven bombs on the same point. So you're talking the Israelis would have to drop 75 or more weapons on the same aim point to have any confidence at all that this would work.
MARGARET WARNER: Even if that operation works, no one's sure how long it would set back Iran's nuclear program back. Even more imponderable is how would Iran respond and what would be the fallout for Israel, the Middle East and the United States?
MATTHEW LEVITT, Washington Institute for Near East Policy: The only thing that's completely certain is that Iran does respond. There's no way Iran doesn't respond. It will respond against Israel primarily.
MARGARET WARNER: Matthew Levitt heads the Counterterrorism and Intelligence Program at the Washington Institute for Near East Policy.
MATTHEW LEVITT: It really all comes down to, how extensive is the strike, the Israeli strike, how many people are killed in that strike, how badly is the nuclear program hurt in that strike, and, therefore, how severe do the Iranians feel they need to respond to such an attack? Because they understand that they will be inviting a response to their response.
MARGARET WARNER: Last week, the supreme leader, Ayatollah Ali Khamenei, promised swift retaliation if any Iranian nuclear sites are hit.
AYATOLLAH ALI KHAMENEI, supreme leader of Iran (through translator): We do not possess nuclear weapons, nor we will make them. But in the face of enemy attacks, whether it is America or the Zionist regime, in defense of ourselves, we will attack them at the same level they have attacked us.
MARGARET WARNER: But there's argument about whether Iran would carry through on that threat.
ALI ALFONEH, American Enterprise Institute: If Iran should engage in a direct military attack against Israel, there's always the risk of U.S. involvement, and the Islamic republic would do anything in its power to avoid U.S. intervention in such a conflict.
MARGARET WARNER: Ali Alfoneh, a resident fellow with the American Enterprise Institute in Washington, believes that risk would keep Iran from retaliating directly against Israeli military targets.
ALI ALFONEH: They know that if they start a conflict which would run, spin out of control, and which would involve the United States, that would be a very, very costly conflict.
MARGARET WARNER: There's another option, Alfoneh said, more advantageous to Iran and the future of its nuclear program.
ALI ALFONEH: On the diplomatic front, Iran would, first of all, mobilize the world opinion against Israel and depict itself as a victim of Israeli aggression. At the same time, such an attack would also legitimize Iran leaving the Non-Proliferation Treaty because within the treaty, there are legal ways of leaving it if the national security of the country is endangered.
MATTHEW LEVITT: I don't find it plausible that if Iran is attacked, it sits back and says I'm going some diplomatic route, leave the NPT, and that's it. That's not how the Iranians operate. That's not how this regime would operate. This would be a shot directly at the revolutionary regime.
MARGARET WARNER: Iran has many tools at its disposal, its own missiles, its Revolutionary Guard and elite Quds strike force, and proxies like Hezbollah militants to Israel's north in Lebanon and Hamas and other militants in Gaza to Israel's south.
Levitt thinks Iran would employ some or all of those to hit multiple targets in the crowded Middle East and Persian Gulf neighborhood, where U.S. warships patrol.
MATTHEW LEVITT: It would very likely carry out attacks using those tools, targeting Israeli, Jewish and probably American and other Western targets as well. We'd see rockets falling on U.S. bases in the Gulf, and we'd probably see some type of effort to block the strait.
MARGARET WARNER: Absurd, says Alfoneh, the Iranian leadership is not suicidal.
ALI ALFONEH: Iran and the Iranian regime is much more interested in survival than in revenge. And that is the policy that they have shown for many, many years.
MARGARET WARNER: But Jeffrey Goldberg sees a danger of escalation even if Tehran's senior leaders choose caution over retaliation.
JEFFREY GOLDBERG: I find a third argument even more plausible, which is that an accident will happen. In other words, the Persian Gulf is filled with these small Iranian speedboats run by the Iranian Revolutionary Guard Corps.
And all it takes is one hyperactive commander acting on his own to ram or try to ram a U.S. ship, and then all hell breaks loose, and it's not because the regime even wanted it. But then you enter into a cycle of escalation that could be extremely dangerous for the United States.
MARGARET WARNER: It is just this unpredictability that keeps Washington policy-makers and many Israeli citizens up at night.