Washington worries the Israelis will bomb Iran's nuclear sites. But can they?

Washington: Two years ago, dozens of Israeli fighter jets roared over the Mediterranean Sea, simulating a strike on Iran's nuclear facilities, a drill the Israeli defense forces openly advertised as an exercise in "long-range flight, aerial refueling and striking distant targets."

The point of the exercise was not simply to intimidate the Iranians. It was also designed to send a message to the Biden administration: The Israeli air force was training to conduct the operation alone, even though chances of success would be far higher if the United States -- with its arsenal of 30,000-pound "bunker busters" -- joined in the attack.

In interviews, former and current senior Israeli officials acknowledged doubts about whether the country has the capability to do significant damage to Iran's nuclear facilities. Nonetheless, for the past few days, Pentagon officials have been wondering quietly whether the Israelis are preparing to go it alone, after concluding that they may never again have a moment like this one.

President Joe Biden has warned them against striking nuclear or energy sites, saying any response should be "proportionate" to the Iranian attack on Israel last week, essentially acknowledging that some counterstrike is appropriate. Defense Secretary Lloyd Austin has been clear with his Israeli counterpart, Yoav Gallant, that the United States wanted Israel to avoid retaliatory steps that would result in new escalation by the Iranians. Gallant is scheduled to meet with Austin in Washington on Wednesday.

It is likely that Israel's first retaliation against Iran for last Tuesday's missile strikes will focus on military bases, and perhaps some intelligence or leadership sites, officials say. At least initially, Israel seems unlikely to go after the country's nuclear crown jewels. After considerable debate, those targets seem to have been reserved for later, if the Iranians escalate with counterstrikes of their own.

Nonetheless, there is a rising call inside Israel, echoed by some in the United States, to seize the moment -- to set back, for years or more, an Iranian capability that US intelligence officials and outside experts increasingly say is at the threshold of producing a bomb. While much of the public discussion has focused on the fact that Iran could almost certainly ramp up enrichment to produce bomb-grade uranium in a matter of weeks, the more relevant fact is that it would take Iranian engineers months or maybe more than a year to fashion that fuel into a deliverable weapon.

"Israel has now its greatest opportunity in 50 years, to change the face of the Middle East," Naftali Bennett, a hard-line nationalist and former prime minister who once described himself as to the right of Prime Minister Benjamin Netanyahu, recently wrote on social media. "We must act *now* to destroy Iran's nuclear program, its central energy facilities, and to fatally cripple this terrorist regime."

He added: "We have the justification. We have the tools. Now that Hezbollah and Hamas are paralyzed, Iran stands exposed."

US officials, starting with Biden, have mounted a campaign to take such strikes off the table, saying they would likely be ineffective and could plunge the region into a full-scale war.

The question of how to strike Iran has become a campaign issue. Former President Donald Trump argued that Israel should "hit the nuclear first and worry about the rest later." It is an approach even he shied away from as president. On Sunday, Rep. Michael R. Turner, the chair of the House Intelligence Committee, criticized Biden on CBS' Face the Nation, saying that "it's completely irresponsible for the president to say that it is off the table, when he's previously said it's on the table."

The sudden debate over a strike has raised new questions. If Israel attacked, how much could it really set back Iran's nuclear capabilities? Or, would the result be simply to drive Iran's nuclear program deeper underground, leading Iran to bar the few nuclear inspectors who still have regular, if limited, access to its major facilities? And what if an Israeli strike prompts Iran's leaders to finally decide to race for a bomb -- the line that Iran's mullahs and generals have, for nearly a quarter of a century, stopped short of crossing?

At Natanz, an old target and a new one

For 22 years, the locus of Israel's attention -- and Washington's -- in Iran has been the Natanz nuclear enrichment plant, buried about three stories into the desert.

Israel has developed plans to destroy or cripple the giant centrifuge hall, where thousands of the tall, silver machines spin at supersonic speeds until the uranium approaches bomb-grade material. While Iran officially denies that it is seeking to possess a bomb, in recent months some Iranian officials and commentators have intensely debated whether a fatwa issued in 2003 by Ayatollah Ali Khamenei, barring the possession of nuclear weapons, should be reversed.

Meanwhile, Iran has stepped up production of uranium enriched to 60% purity, just shy of bomb grade. It now has enough of that fuel for three or four bombs, experts believe, and getting it to bomb grade, at 90%, would take just days.

While Natanz would be a fairly easy target, hitting it would be an act of war. So for the past 15 years, the United States has urged diplomacy, sabotage and sanctions, not bombs, to foul up the program. And it has actively blocked Israel from getting the weapons it would need to destroy another centrifuge facility, called Fordo, built deep in a mountain.

President George W. Bush turned aside Israel's demands to give its air force the United States' biggest bunker-busting bombs, and the B-2 bombers that are needed to deliver them. Those weapons would be essential to any effort to take out Fordo and other deep, heavily reinforced facilities.

Bush's decision touched off an argument inside the White House. Vice President Dick Cheney embraced the idea of a strike, but Bush held fast, arguing that the United States could not risk another war in the Middle East. Ehud Barak, who served as Israel's highest-ranked uniformed officer and also as prime minister, said in an interview with The New York Times in 2019 that Bush's warning "did not really make any difference for us." As of the end of 2008, he said, Israel did not have a feasible plan for attacking Iran.

It soon developed several. The argument over the bunker busters helped give birth to a huge covert operation known as "Olympic Games," a highly classified Israeli-American program to destroy the centrifuges using a cyberweapon. More than 1,000 centrifuges were destroyed by what became known as the Stuxnet virus, setting the program back by a year or more.

But Olympic Games was no silver bullet: The Iranians rebuilt, adding thousands more centrifuges. They moved more of their effort deep underground. And the fact that the malicious computer code escaped the plant, and was revealed to the world, prompted other countries to focus on developing their own infrastructure attacks, including electric grids and water systems.

The Israelis also assassinated scientists and struck aboveground enrichment facilities, attacked centrifuge-manufacturing centers with drones and invested huge resources in preparation for a possible attack on the facilities.

The Israeli efforts faltered after the Obama administration reached a nuclear deal with Iran that led the country to ship much of its nuclear fuel out of the country. And later, when Trump pulled out of the deal, he and Netanyahu were convinced the Iranians would give up their projects in response to Washington's threats. The Israeli military focused instead on Hezbollah, and the underground tunnels where it stored Iranian-produced missiles.

When Bennett became prime minister in 2021, Israeli officials say, he was shocked by Israel's lack of preparedness to attack the Iranian program, ordering new exercises to simulate flying the long distances to Iran and pouring new resources into the preparations. Even today, Israel's capability is limited. The country relies on an aging fleet of Boeing 707 aerial refueling planes, and it will be years before newer models, capable of carrying fuel for far longer ranges, are delivered by the United States.

Israel's own bunker busters have been effective against the kinds of tunnels where Hezbollah stores missiles, and they enabled Israeli forces to kill Hassan Nasrallah, the Hezbollah leader, last month. The Israelis believe they can take out the air defenses around many of the nuclear sites; they hit one, to send a message, in a missile exchange with Iran in April. But Israel simply cannot get into highly reinforced nuclear facilities dug into mountains.

"The nuclear target is a very difficult target," said Gen. Frank McKenzie, who was in charge of the Iran war plans when he ran United States Central Command. "There are a lot of other alternatives to that target," he said, adding that many of them -- including energy infrastructure -- would be easier to execute.

Iran's next moves

Whether Israel strikes Iran's nuclear facilities or not, there are new reasons for concern about Iran's nuclear future.

The first is one that Secretary of State Antony Blinken has raised repeatedly in recent weeks: He has asserted, based on intelligence the United States declines to talk about, that Russia is sharing technology with Iran on nuclear issues. Officials describe the help as "technical assistance" and say there is no evidence that it is providing Iran with the hardware it needs to make a warhead.

But until the war broke out in Ukraine, Russia had cooperated with the United States and Europe in restraining the Iranian nuclear program, even joining the 2015 negotiations on the side of Western nations. Now, if the American reports are right, Russia's need for Iranian drones and other weaponry means it could speed Iran's progress toward building a nuclear device.

The second concern is that the damage done to Hezbollah in the past few weeks, including the decapitation of its leadership, could make Iran feel vulnerable. It can no longer count on the terror group's ability to strike into Israel. Moving to obtain a nuclear weapon might become its only real way to deter Israel.

And the third concern is that the Iranian program will only get harder to hit. Several years ago, under the watchful eyes of American and Israeli satellites, Iran began digging a vast tunnel network just south of Natanz, for what the United States believes is a new enrichment center, Iran's largest. It is not yet up and running. In the past -- when Israel destroyed not-yet-complete nuclear reactors in Iraq in 1981 and Syria in 2007 -- that is exactly the moment it chose to mount preemptive attacks.