Behind the Tactical Gains Against Iran, a Longer-Term Worry

Experts inside and outside the Biden administration fear that Iran may conclude it has only one defense left: racing for an atomic weapon.

When Israeli fighter jets roared off the runways on Friday night, on a thousand-mile run to Iran, they headed for two major sets of targets: the air defenses that protect Tehran, including Iran’s leadership, and the giant fuel mixers that make propellant for Iran’s missile fleet.

Israel’s military leaders, in calls with Defense Secretary Lloyd J. Austin III and other senior American officials, had concluded that taking out the air defenses would make Iran’s leaders fearful that Tehran itself could not be defended. That feeling of vulnerability was already high, after Israel decimated the leadership of Hamas and Hezbollah, Tehran’s proxy forces that could strike Israel, over the past month.

The surprise element for the Iranians was a set of strikes that hit a dozen or so fuel mixers, and took out the air defenses that protected several critical oil and petrochemical refineries, according to a senior U.S. official and two Israeli defense officials who spoke on condition of anonymity to discuss internal planning.

Without the capability to mix fuel, Iran cannot produce more of the type of ballistic missiles that its forces fired on Israel on Oct. 1, the immediate provocation for Israel’s strike. And it could take more than a year to replace them from Chinese and other suppliers.

By Saturday, American and Israeli officials were claiming a major success, but lurking behind the satisfaction with the tactical gains lies a longer-term worry. With Iran’s Russian-produced air defenses in smoldering piles, many fear the Iranian leaders may conclude they have only one defense left: racing for an atomic weapon.

That is just what American strategists have been desperately trying to avoid for a quarter-century, using sabotage, cyberattacks and diplomacy to keep Tehran from crossing the threshold to become a full nuclear-armed power.

President Biden, who had publicly warned Israel three weeks ago to avoid hitting Iran’s nuclear and energy sites out of fear that the conflict would escalate into a regional war, seemed satisfied, for once, that Prime Minister Benjamin Netanyahu of Israel had listened to him.

“It looks like they didn’t hit anything but military targets,” Mr. Biden told reporters on Saturday after receiving an intelligence assessment along with Vice President Kamala Harris, who was not counting on an expanding war in the Middle East while she is in the last 10 days of her campaign for president.

“I hope that this is the end,” he said.

That seems unlikely. Even Mr. Biden’s own aides suspect that Iran’s leaders, partly out of injured pride, will not simply let the counterattack pass. Mr. Biden ordered American troops in the region to be on higher alert, especially those in Iraq and Syria who could be targets for Iranian retaliation. Last week, American forces put in place an additional air defense unit that had been sent to Israel, and the Gulf has been abuzz as extra squadrons of F-16s, F-15Es and A-10 Warthogs have come in to supplement a large existing aerial force.

Iran’s supreme leader, Ayatollah Ali Khamenei, was reportedly meeting with the top ranks of the Islamic Revolutionary Guard Corps to determine his next steps and took a measured tone in his first remarks on the attacks, saying they should not be “magnified or downplayed.” And apart from vague, tough-sounding warnings from other Iranian officials about defending the nation’s sovereignty, there was little evidence that any decision had been made on a response.

“The Israelis just demonstrated extraordinary capabilities, while keeping their complex, multiwave strikes precise and carefully calibrated,” said Dana Stroul, formerly the Pentagon’s top Middle East policy official and now a senior fellow at the Washington Institute for Near East Policy. “By only targeting military facilities and striking at a time of day that was designed to avoid significant casualties, the Iranians have been given a path to de-escalate.”

Ms. Stroul said that if Iran chose to escalate, its critical military, leadership and nuclear facilities were more exposed than ever. “The table is set for de-escalation if Iran chooses to do so,” she said. “Otherwise, the next Israeli response will be even more destructive.”

Four American officials and three Israeli defense officials, who spoke on condition of anonymity to discuss confidential planning, echoed that assessment.

Even if Iran decides against another missile strike at Israel — and takes the risk that Israel’s air force will come back to wreak more damage, including on the energy infrastructure critical to Iran’s battered economy — its leaders have another choice. Publicly or secretly, they could reverse the ayatollah’s ostensible ban on building a nuclear weapon.

The country has never been closer to the nuclear threshold. Iran now has larger stocks of near-bomb-grade uranium than at any time since it began experimenting with small nuclear reactors, including one provided to the shah by the United States, before the 1979 Islamic revolution.

Based on reports from the International Atomic Energy Agency, a United Nations-created inspection body, Iran now has enough medium-enriched uranium to produce three to four weapons. That is thanks to a production spurt that began shortly after President Donald J. Trump pulled out of the Iran nuclear agreement in 2018. Up until that point, Iran had kept within the tight production limits it had agreed to as part of the accord, reached with the Obama administration, that lifted sanctions in return.

But it has spent the past four years engaging in a sharp technical upgrade, as the country’s ruling elite is dropping its decades-old insistence that the nation’s nuclear program is entirely peaceful. Now it is a “threshold” nuclear power, capable of further enriching its fuel to make bomb-grade uranium in a matter of days or weeks.

It would take far longer, upward of 18 months, to actually fashion that fuel into a warhead, assuming that Iran does not get help from an established nuclear power — such as Russia, its biggest customer for drones, or North Korea, with whom it worked closely on ballistic missile technology.

So far, American officials say, they see no evidence of a political decision by the Iranians to race for a weapon. But as one senior American official said, countries build nuclear weapons when they are feeling vulnerable. And today, that is exactly Iran’s national emotion.

Mr. Biden has been intensely focused on the Iranian nuclear program since his days in the Senate, and he was a major participant in the Obama administration’s debates over using a cyberweapon, later called Stuxnet, to destroy Iran’s nuclear centrifuges at Natanz.

In the days after the Oct. 1 strike by Iran, which came after the killing of Hezbollah’s leader, Hassan Nasrallah, in an airstrike in Lebanon, Mr. Biden was explicit in warning Israel to keep energy and nuclear sites off its retaliation list.

Israeli officials celebrated the fact that the Iranian attack did little damage, though some Israeli and American officials said they were lucky to have escaped worse destruction. Initially, Israel’s leadership was tempted to retaliate by striking at Iran’s prized assets. But they pared that back soon after Mr. Biden said he would not support any counterstrike that could trigger a wider regional war.

When a reporter asked Mr. Biden specifically about hitting Iran’s nuclear facilities — an operation Israeli forces have practiced often — the president made clear he would consider that a step too far.

“The answer is no,’’ he said. Noting he had convened leaders of the Group of 7, which includes Britain, France, Germany, Italy, Japan and Canada, he added that “all seven of us agree that they have a right to respond, but they should respond in proportion.”

Israeli officials insist they made their own decisions about what to strike, and did not give in to American pressure as they selected targets. But they did offer to give advance warning about their timing and plans — something they had failed to do in some previous strikes — and the United States agreed to quickly renew the stockpile of weapons drawn down for the strike. Mr. Biden acknowledged to reporters a week ago that he knew about both the timing and targets.

Still, there was considerable behind-the-scenes debate on how to narrow the attack. On Oct. 19, Mr. Austin spent most of the lunch break during a security meeting of Group of 7 countries in Naples speaking by phone to Yoav Gallant, his Israeli counterpart, who was in charge of formulating Israel’s strategy. What emerged from the series of conversations was a plan designed to deter Iran from retaliating by exposing the leadership and military and energy facilities to a quick counterstrike. But attacking the fuel mixers sent an additional message: Israel would focus on crippling Iran’s ability to expand its potent missile fleet.

The Israelis also had to negotiate around several diplomatic hurdles after Iran urged neighboring states not to allow Israeli jets to use their airspace to mount an attack. Many complied, including Jordan, which had participated in intercepting Iranian missiles in April. (The Jordanians say they will help defend Israel, but they draw the line at participating in offensive strikes or letting Israelis fly over their territory.)

In the end, the Israelis did not fly over Jordan. They routed mainly through Syria and, to a lesser degree, Iraqi airspace, from which they fired into Iran, according to a statement from Iran’s armed forces. U.S. officials would not say what kind of arrangements were made — if any — with the Iraqi government, and referred all questions to the Israelis.

The only glitch was in timing: Bad weather over the targets delayed the Israeli strikes by a few days, American and Israeli officials said. The U.S. officials suspect that Israeli officials did not want to launch the attack while Secretary of State Antony J. Blinken was in the region looking to revive cease-fire and hostage-release agreements over Gaza and a pause in the fighting in Lebanon.

He made little progress, and the Israeli fighter jets took off from their bases just as Mr. Blinken was landing back in Washington.

On Saturday, right-wing members of Mr. Netanyahu’s coalition lamented that the strikes did not go far enough.

Itamar Ben-Gvir, the hard-line national security minister, who had urged Mr. Netanyahu to go directly at Iran’s nuclear production site, said Saturday’s attack should be regarded as an “opening blow.”

But while Mr. Ben-Gvir is considered on the extreme right, he was joined in the critique by Yair Lapid, the centrist leader of the parliamentary opposition. He argued that Mr. Netanyahu had made a mistake in heeding Mr. Biden’s warnings.

“The decision not to target strategic and economic targets in Iran was a mistake,” he said. “We could and should have made Iran pay a much higher price.”

Aaron Boxerman contributed reporting from Jerusalem and Alissa J. Rubin from Beirut.