Amid this relative calm, the United Nations has renewed its call for a diplomatic solution to the Iran nuclear issue, warning that the objectives of the Joint Comprehensive Plan of Action (JCPOA) – and the resolution that endorsed it – remain unmet.

Addressing a planned Security Council meeting on Tuesday to try and revive the deal amid the dramatic military escalation of the past 12 days, UN political affairs chief Rosemary DiCarlo said the fragile ceasefire announced by Donald Trump overnight provided “an opportunity to avoid a catastrophic escalation and achieve a peaceful resolution of the Iran nuclear issue.”

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The 2015 Iran nuclear deal – more formally known as the JCPOA and backed by the Security Council – offered Tehran sanctions relief in exchange for strict limits on uranium enrichment, stockpile levels and centrifuge use, alongside robust monitoring and verification by the International Atomic Energy Agency (IAEA).

But the accord has remained in limbo since the United States withdrew in 2018, followed by Iran’s rollbacks of its nuclear-related commitments.

With key provisions under resolution 2231 set to expire on 18 October – unless the Council decides otherwise – the UN’s top political official has warned that the window for reviving diplomacy is narrowing.

With less than four months before resolution’s remaining nuclear-related restrictions are set to expire on 18 October – unless extended by the Council – the UN’s top political official warned that the agreement’s key aims remain elusive.

Diplomacy kneecapped?

Ms. DiCarlo told ambassadors the recent surge in violence had significantly undermined diplomatic momentum.

“The military escalation between Israel and Iran since 13 June and United States air strikes on Iran’s nuclear facilities on 21 June complicated prospects for achieving full implementation of resolution 2231,” Ms. DiCarlo said.

“Iran’s strikes yesterday on a base in Qatar further exacerbated insecurity in an already tense region.”

Despite five rounds of bilateral talks between Iran and the US, facilitated by Oman in recent months, Ms. DiCarlo noted that efforts “did not produce a way forward” to restore full JCPOA implementation.

A sixth round of talks was called off due to the outbreak of hostilities.

Meanwhile, the toll from the recent conflict has been sobering. According to Iranian authorities, at least 606 people were killed and more than 5,300 injured since hostilities erupted on 13 June. Israeli officials reported 28 deaths and nearly 1,500 injuries.

Time running out

While divisions persist, Ms. DiCarlo said JCPOA participants – China, France, Germany, Iran, Russia, and the United Kingdom – had all reiterated their commitment to finding a diplomatic solution.

In a joint statement shared with the Secretary-General in March, China, Iran and Russia stressed the importance of resolution 2231’s provisions and timelines. China separately proposed a “step-by-step and reciprocal approach” to settle the nuclear issue.

“Diplomacy, dialogue and verification remain the best option to ensure the exclusively peaceful nature of Iran’s nuclear programme,” Ms. DiCarlo said.

UN Photo/Eskinder Debebe EU Ambassador Stavros Lambrinidis briefs the Security Council as the Coordinator of the Joint Commission established by the JCPOA.

Deal, not force, key to resolution: European Union

Echoing UN appeals for dialogue, the European Union stressed that “a lasting solution to the Iranian nuclear issue can only be through a negotiated deal, not military action.”

Briefing the Council on behalf of EU High Representative Kaja Kallas, Ambassador Stavros Lambrinidis underscored the urgent need “to come back to a diplomatic solution.”

Ensuring that Iran does not acquire or develop a nuclear weapon remains a key security priority for the EU, he said.

He added that Iran’s accelerating nuclear activities and the absence of IAEA oversight – compounded by the economic fallout from US sanctions – have severely undermined the JCPOA, despite sustained EU efforts to preserve it through diplomacy.

Mr. Lambrinidis reaffirmed that diplomacy must prevail, with the IAEA remaining central to monitoring and verification efforts going forward.

US urges Iran to return to talks

Ambassador Dorothy Shea, Acting US Representative, said Iran’s increase in nuclear activity lacked “any credible civilian justification.”

Even after the IAEA Board of Governors found it noncompliant with nuclear safeguards, she noted, “it is regrettable that certain members of this Council have opted to turn a blind eye to, if not encourage, Iranian noncompliance.”

The US “will not turn a blind eye to Iran’s noncompliance and ongoing threat to regional stability,” she continued.

Ambassador Shea said the 21 June “precision operation effectively fulfilled our narrow objective – to degrade Iran’s capacity to produce a nuclear weapon,” after which President Trump coordinated a ceasefire between Iran and Israel.

“In this critical moment,” she concluded, “we must all urge Iran to seize this opportunity for peace and prosperity and abide by its international obligations.”

UK calls ceasefire a first step

UK Ambassador Barbara Woodward welcomed the ceasefire brokered by President Trump but warned that “the situation remains extremely fragile.”

Expressing that “now is the time for a return to diplomacy,” she urged Iran to engage in talks without delay, warning that its nuclear programme has exceeded “any credible civilian justification.”

She said all diplomatic levers will be deployed for a negotiated outcome and to “ensure Iran does not develop a nuclear weapon.”

Video feed of the Security Council meeting.

Iran: Diplomacy can and must resolve differences

Iran’s Ambassador, Amir Saeid Iravani, said that his country “never initiated this war” and that “once the aggressors stopped their attacks, Iran stopped its lawful military response as well”.

Mr. Saeid also expressed his country’s strong commitment to diplomacy as the path through which differences can and should be resolved.

“Iran continues to believe that a diplomatic resolution to nuclear and sanction issues is possible,” Mr. Saeid said.

He called on the Security Council to condemn Israel’s and the United States’ attacks on Iran and their IAEA-protected nuclear facilities and work to ensure that they never happen again.

Ambassador Iravani added that Iran upheld Council resolution 2231 and the JCPOA, and that remedial measures were “fully consistent” with these two instruments.

Israel warns diplomacy with Iran has failed

Israeli Ambassador Danny Danon defended his country’s military operation against Iran, describing it as a necessary move to neutralise a “double existential threat” from Tehran’s nuclear and missile programmes.

He said Israel achieved complete air superiority and removed key regime targets, acting in coordination with the US.

Ambassador Danon accused Iran of deceiving the world for years, using diplomacy as cover to advance its nuclear weapons programme.

“There is still time,” he said, “to take meaningful and decisive action to ensure that the threat of a nuclear Iran does not return stronger than before.”

“We are often told that diplomacy must be given a chance – it was given every chance, every round, every channel, every deadline – but so far it has failed, the regime in Tehran never had any intention of complying.”

European foreign ministers pushed Iran to return to direct talks with the U.S.

President Vladimir Putin of Russia said he was concerned that conflicts over Ukraine and Iran could spark World War 3.

With the threat of U.S. airstrikes, President Trump used “coercive diplomacy” to force possible Iranian nuclear concessions.

Iran’s top diplomat rejected negotiations over Tehran’s nuclear program while Israeli bombs continue to fall, making a ceasefire in the eight-day war a condition for renewed talks with the Trump administration.

Foreign Minister Abbas Araghchi’s statement came a day after President Donald Trump opened a possible two-week window for talks, turning down expectations of imminent U.S. airstrikes on Iran’s nuclear facilities.

“There is no room for negotiations with the U.S. until Israeli aggression stops,” Araghchi was quoted as saying on Iranian state TV on June 20. Talks later in the day between Araghchi and his counterparts from the UK, France, Germany and the EU ended after three hours without a breakthrough. The talks, which aim to get Iran back into negotiations with the Trump administration, will continue, participants said.

Trump told reporters “two weeks would be the maximum,” time he will wait to strike a deal with Iran before greenlighting aggressive action.

While diplomats wrangled in Geneva and at the UN in New York, the airstrikes kept coming. Israel said it hit Iranian missile facilities overnight, while an Iranian missile stuck in southern Israel. Iran said June 16 that 240 people had been killed in Israeli attacks. The Human Rights Activists News Agency, a U.S.-based group focused on Iran, said more than 600 had died. At least 24 Israelis have been killed by Iranian fire.

Follow along with USA TODAY for live updates of the Israel-Iran crisis.

Trump dismisses intelligence community assessment on Iranian nuclear program again

Trump knocked down an intelligence community assessment that Iran is not building a nuclear weapon.

He told reporters after landing in New Jersey that Director of National Intelligence Tulsi Gabbard was “wrong” when she said that in testimony earlier this year to Congress.

It was the second time this week that Trump has publicly disputed the findings from the U.S. intelligence community on Iran, after telling reporters on June 17, “I don’t care what she said.”

-Francesca Chambers

Trump: Iran has 2 weeks to make a deal

President Donald Trump in his first public remarks in nearly 48 hours said Iran has a maximum of two weeks to make a deal with the United States before he approves aggressive action against the Islamic Republic.

“I’m giving them a period of time,” Trump said of Iran while speaking to reporters in New Jersey. “Two weeks would be the maximum.”

Trump said he did not understand why oil-rich Iran would need enriched uranium for civilian energy purposes and told press traveling with him that he would be willing to consider a ceasefire in the conflict.

The president said he was waiting “to see whether or not people come to their senses” and said that “Iran doesn’t want to speak to Europe, they want to speak to us,” as he dismissed U.S. allies’ Geneva talks.

The president is spending the night at his Bedminster golf club, where he’ll appear in the evening at a MAGA Inc. fundraiser. He is liable while he is there to hear from backers of his movement who are opposed to military action.

He told reporters before he boarded Marine One that he can still play peacemaker if he does decide to strike. “Sometimes you need some toughness to make peace but always a peacemaker,” he said.

-Francesca Chambers

State Department tight-lipped on conflict with Iran

State Department spokeswoman Tammy Bruce was tight-lipped at an afternoon briefing, where she was pressed for information on conversations the adminstration may be having with Iran.

She said President Trump is “not posturing” and wants a diplomatic solution. But she could not say why Trump put two-week timer on negotiations.

“He has his reasons, and he’s the one who knows, and that is the specificity of his statement, and I’ll leave it at that,” Bruce said. Trump on June 20 said he had opened a two-week window for new talks with Iran before deciding if the U.S. should join Israel’s airstrikes on Iranian uranium enrichment sites.

-Francesca Chambers

Shortage of Israeli missile interceptors could force ‘serious decisions’ on U.S.

As Israel downs incoming volleys of Iranian missiles, a shortage of its missile interceptors could put both the U.S. and Israel in a bind.

After a week of aerial war with Iran, Israel’s long-range Arrow interceptors are running low, the Wall Street Journal reported on June 18. In addition to Arrow interceptors, which are Israeli-made, Israel also has U.S.-made THAAD batteries, which intercept medium-range ballistic missiles.

If the U.S. chooses to replenish Israel’s missile interceptors, it would mean drawing from other stockpiles, since Congress wouldn’t have time to surge U.S. defense production of more, according to Brandan Buck, a research fellow at the Cato Institute.

That could include siphoning off THAAD interceptors from Ukraine, those marked off to defend Taiwan, or the U.S.’s own national stock, Buck said.

“If they truly do run out… that’s going to put us in a position in which we have to make some serious decisions,” Buck said.

-Cybele Mayes-Osterman

No breakthrough in Europe talks

The foreign Ministers of France and Germany and the High Representative of the European Union said in a statement after three hours of talks with Iran that the group “discussed avenues towards a negotiated solution to Iran’s nuclear program.”

“They expressed their view that all sides should refrain from taking steps which lead to further escalation in the region, and urgently find a negotiated solution to ensure that Iran never obtains or acquires a nuclear weapon,” the statement said.

The Europeans are trying to get Iran back negotiating with the U.S. under the shadow of President Trump’s threat to join Israel’s air war on the Iranian nuclear program.

-Francesca Chambers

UN chief warns of uncontrollable conflict

Israel’s U.N. envoy, Danny Danon, told the Security Council his country would not stop its attacks “until Iran’s nuclear threat is dismantled.” Iran’s envoy Amir Saeid Iravani called for Security Council action and said Tehran was alarmed by reports the U.S. may join the war.

The head of the U.N. nuclear watchdog used the June 20 meeting at the United Nations in New York to warn against attacks on nuclear facilities. “Armed attack on nuclear facilities… could result in radioactive releases with great consequences within and beyond the boundaries of the state which has been attacked,” International Atomic Energy Agency director Rafael Grossi said.

He spoke a day after an Israeli military official said it had been “a mistake” when a spokesperson said Israel had struck Bushehr, Iran’s only nuclear power plant. Iran said on its air defences had been activated in Bushehr, without elaborating.

U.N. Secretary-General Antonio Guterres warned the conflict could “ignite a fire no one can control” and called on all parties to “give peace a chance.” Russia and China demanded immediate de-escalation.

The White House said on Thursday President Donald Trump would decide on U.S. involvement in the conflict in the next two weeks. A three hour meeting on June 20 between European foreign ministers and Iran ended without apparent progress.

-Reuters

Putin says he fears World War 3

Russian President Vladimir Putin said he was worried when asked if he was concerned the world was heading towards World War Three.

Putin, speaking at an economic forum in St Petersburg on June 20, said world conflict was growing.

He mentioned Russia’s own war in Ukraine, the conflict between Israel and Iran, and said he was concerned by what was happening around nuclear facilities in Iran where Russian specialists are building two new nuclear reactors for Tehran.

“It is disturbing. I am speaking without any irony, without any jokes. Of course, there is a lot of conflict potential, it is growing, and it is right under our noses, and it affects us directly,” said Putin.

On June 18, Russian foreign ministry spokeswoman Maria Zakharova said Israeli strikes on Iranian nuclear infrastructure put the world “millimeters” from catastrophe.

-Reuters

Vladimir Putin: Trump agrees to protect Russian-operated reactor in Iran

Russian leader Vladimir Putin said President Trump had agreed to ensure the Israelis don’t strike the Russian-operated Bushehr nuclear reactor in Iran.

On June 19, the Israeli military mistakenly announced that Bushehr, Iran’s only nuclear power plant, had been hit by an airstrike. The claim was later retracted, but it sent a wave of concern across the region. Bushehr is on Iran’s southern coast, not far from other Persian Gulf nations.

The head of Russia’s nuclear energy corporation warned an attack on Bushehr could lead to a “Chernobyl-style catastrophe.”

Russian reports on June 20 said both Trump and the Israeli government had agreed to safeguard the safety of Russian staff at Bushehr.

The 3,000 megawatt plant isn’t connected to Iran’s nuclear enrichment program. Spent fuel is shipped back to Russia, making it unavailable for enrichment in Iran.

-Dan Morrison

Iran says European spy arrested

Iran’s semi-official Tasnim news agency said a European posing as a tourist had been charged with espionage in northern Iran after they were caught with photos of sensitive military installations. The suspect wasn’t named. The report came as officials separately announced they had arrested “internal agents of the enemy,” and encouraged Iranians to watch out for spies.

The reported arrests came in the wake of a massive operation in which Israeli forces were able to knock out key parts of Iran’s nuclear and military infrastructure in a surprise attack on June 13, while killing top generals and nuclear scientists in targeted strikes on their homes and other locations.

Israel spent years smuggling weapons into Iran, where it established a secret base for explosive-laden drones that later savaged Iranian targets, and positioned short-range weapons near Iranian surface-to-air missile systems, according to U.S. and Israeli media reports.

Now, Iran’s Revolutionary Guards are on the hunt for enemies within who may have helped Israel prepare its devastating blow. A security official quoted by Tasnim praised the “timely reporting of suspicious activities.”

-Dan Morrison

Back to the nuke deal future?

As President Donald Trump delays a decision on bombing Iran’s nuclear sites, giving time for European nations to pursue diplomacy, two numbers loom over any future nuclear accord: 3.67% and 90%.

The first number was the level of uranium enrichment the United Nations’ nuclear watchdog verified Iran was enriching at around the time Trump, in his first term, pulled the United States out of the Obama-era nuclear deal, known as JCPOA, between Iran and world powers.

Since Trump scrapped the deal in May 2018 Iran’s enrichment level has closed in on 90%, according to the International Atomic Energy Agency. That’s the level, the IAEA and other nuclear watchdogs say, that puts Iran on the cusp of turning enriched uranium into a nuclear weapon.

The JCPOA’s critics, many of them decades-long Iran hawks such as former national security adviser John Bolton and Sens. Ted Cruz and Marco Rubio (now U.S. Secretary of State), have long pointed out that the accord did nothing to address Iran’s ballistic missile program and its regional militia proxies.

But the enrichment controls were, according to the IAEA, working. This raises questions about what kind of new deal could potentially emerge, and if it will be an improvement on what Trump abandoned in 2018.

-Kim Hjelmgaard

Europe pushes Iran to rejoin U.S. talks

European diplomats sat down with Iran’s foreign minister in a last-ditch effort to restart U.S.-Iran nuclear talks.

Presidential envoy Steve Witkoff and Secretary of State Marco Rubio met at the White House on June 19 with UK Foreign Secretary David Lammy, who is now in Geneva for the European talks with Iranian Foreign Minister Abbas Araghchi.

“A window now exists within the next two weeks to achieve a diplomatic solution,” Lammy said in a post on X.

Rubio has been burning up the phones with his European counterparts, including French Foreign Minister Jean-Noël Barrot. Working with the Trump administration’s blessing, the Europeans called “for a return to the diplomatic track and to continue negotiations on Iran’s nuclear program,” the French foreign ministry said.

President Trump on June 19 opened a two-week window for talks to end Iran’s nuclear program, under the threat of the U.S. joining Israel’s airstrikes.

-Francesca Chambers

Iran says Israel sabotaged its talks with Trump administration

Iranian foreign minister Abbas Araghchi said his government was preparing a “very promising” proposal for the Trump administration in talks over its nuclear program when Israel attacked on June 13.

Araghchi on June 20 called Israel’s attacks on Iranian nuclear facilities and other targets grave war crimes, speaking at the United Nations in Geneva, Switzerland, ahead of talks with European diplomats.

Iranian and U.S. negotiators were set to meet on June 15. Araghchi said Israel had betrayed diplomacy by striking before that planned round of U.S.-Iran talks.

President Trump has said repeatedly Iran should have accepted a U.S. offer. The details of Washington’s offer aren’t publicly known, except for a single condition: A complete end to nuclear enrichment, which Iran says it can’t accept.

“They had to sign a document, and I think they wished they signed it,” Trump said June 18. “It was a fair deal, and now it’s a harder thing to sign.”

Trump, weapons massed, uses ‘coercive diplomacy’

Former U.S. ambassador to Israel Daniel Shapiro said the Pentagon has for years been refining plans for strikes on Iran that President Donald Trump can tap into if he decide to give the go-ahead.

“He’s clearly ordered the forces into the theater that would support the strike if and when he makes that decision,” said Shapiro, who was deputy assistant secretary of defense for the Middle East at the end of the Biden administration.

U.S. airstrikes could also prompt retaliation. Tehran’s response could include attacks on U.S. military bases in Gulf countries or Iraq and Syria, the targeting of regional energy facilities, and blocking oil and gas shipments from crossing the Strait of Hormuz, Shapiro said.

The conflict is now in a phase of “coercive diplomacy,” where Trump is signaling that he’s preparing for military strikes, he said.

“There’s potentially one last opportunity for Iran to come to a negotiating table, whether it’s with the U.S. or through some other partners, and make the concession that they wouldn’t make in the talks that were being held before the hostility started,” Shapiro, a fellow at the Atlantic Council, told USA TODAY.

-Francesca Chambers

Explosions over Tel Aviv

For the eighth day in a row, the consussion of missile and interceptors echoed over Tel Aviv. Iranian news reports said a new fusillade of missiles had been fired toward Israel.

Israeli officials said they were working to intercept the ballistic missiles. While taking a pummeling from Israel, Iran has managed several times to pierce its enemy’s “Iron Dome” defensive shield, striking neighborhoods, hospitals and a research institute.

Prime Minister Benjamin Netanyahu of Israel has argued that the attack on Iran was to stop Tehran from developing a nuclear weapon, even as a sixth round of talks to prevent that very outcome was scheduled between the United States and Iran.

While Israel argues that it had to strike now to prevent an Iranian race to bomb, American and European judgments were that Iran was still many months away from building a bomb and has not yet decided to do so.

Mr. Netanyahu believes that a deal that would allow Iran to enrich uranium would mean a nuclear-armed Iran in the future, and he has been bent on preventing that outcome. He has apparently judged that a U.S.-Iran deal would have kept him from his goal of destroying Iran’s nuclear program, and, perhaps, he hopes, bringing about the fall of the Islamic Republic.

But Israel is considered highly unlikely to meet the goal of destroying Iran’s nuclear program without active American involvement, which Mr. Trump has so far resisted.

The president continues to say that he wants negotiations to succeed. He seems to believe that the attack will bring Iran back to the table in a weaker and more conciliatory position, ready to accept his latest demand that it halt all enrichment of uranium. But Iran insists that it has the right to enrich for civilian uses under the Nuclear Nonproliferation Treaty.

Mr. Trump clearly sees the war as a form of diplomacy. On Friday, he wrote: “Two months ago I gave Iran a 60-day ultimatum to ‘make a deal.’ They should have done it! Today is day 61. I told them what to do, but they just couldn’t get there. Now they have, perhaps, a second chance!”

Early on Sunday, Mr. Trump warned Iran against attacking American forces in a message on Truth Social. “However, we can easily get a deal done between Iran and Israel, and end this bloody conflict,” he said. Whether Israel would accept such a deal, if Iran is allowed to enrich at all, is an open question.

At the same time, Mr. Trump, who has said he knew about the Israeli attack beforehand, has done nothing in public to restrain the Israelis. When Washington announced last week that the talks would continue on Sunday, it is not clear whether it knew when Israel would attack, but the Iranians are convinced that Washington was complicit in trying to fool them into believing that any Israeli attack would come afterward.

A quick deal now that would give up enrichment would be seen as a surrender, said Vali Nasr, a professor at the Johns Hopkins School of Advanced International Studies who served in the State Department during the Obama administration. That could make the Iranian government more vulnerable at home. “They won’t give up enrichment, not this easily,” he said. “They’re not going to surrender.”

The American B-2 stealth bomber is the only plane capable of carrying the bombs needed to strike Iran’s deepest nuclear facilities, but the decision to use them is not without risk.

It sounds so surgical, so precise, exactly the kind of air attack that only the U.S. Air Force can execute.

A series of B-2 bombers lifts off from Whiteman Air Force Base in Missouri or the island of Diego Garcia in the Indian Ocean. Refueled in the air, they head for a remote mountain in north-central Iran, far from civilians, where they get Iran’s most heavily fortified nuclear site, Fordo, in their sights.

They drop their giant 30,000-pound bunker-busters, one after another, blasting a giant hole down to the centrifuge halls that have been in the bull’s-eye of the American military since President Barack Obama and the leaders of Britain and France revealed the existence of the plant in the fall of 2009, charging Iran with a great “deception.”

Few potential operations, with the possible exception of a Chinese invasion of Taiwan, have been so examined, rehearsed and debated. Technically, the military and geological experts say, it should be doable.

And yet it is full of risks — known unknowns and unknown unknowns, as the former defense secretary Donald Rumsfeld used to say in the context of the Iraq War, another rabbit hole of American military action in the Middle East. That is why it has given pause to every American president who has looked at it for the past 16 years.

President Trump on Wednesday emphasized that he had yet to make a decision to drop what in private he calls “the big one.” But gone was the bellicose tone that characterized his public utterances a day earlier. In its place was a note of caution. “I may do it,” he told reporters on the White House’s South Lawn. “I may not do it. I mean, nobody knows what I’m going to do.”

Meanwhile, the Iranians, after five days of remarkable losses to the Israelis, seemed to be looking for a way out. Iran’s supreme leader, Ayatollah Ali Khamenei, issued a defiant response to Mr. Trump’s call for “unconditional surrender,” but Mr. Trump said there were indications that the Iranians wanted to talk, and reports of an official Iranian plane landing in Oman, where many of the negotiations with Steve Witkoff, the president’s special envoy, had taken place before Israel’s attack.

If Mr. Trump is taking a pause, it may be because the list of things that could go wrong is long, and probably incomplete. There’s the obvious: It’s possible that a B-2 could get shot down, despite Israel’s success of taking out so many of Iran’s air defenses. It’s possible the calculations are wrong, and even America’s biggest conventional bomb can’t get down that deep.

“I’ve been there, it’s half a mile underground,” Rafael Grossi, the director general of the International Atomic Energy Agency, said last week, as the Israeli operation began.

But assuming that the operation itself is successful, the largest perils may lie in the aftermath, many experts say, just as they did in Afghanistan and Iraq. There are many lessons from that ugly era of misbegotten American foreign policy, but the most vital may be that it’s the unknown unknowns that can come back to bite.

Iran has vowed that if attacked by American forces, it would strike back, presumably against the American bases spread around the Middle East and the growing number of assets gathering in the Persian Gulf and the Mediterranean. All are within missile range, assuming Iran has missiles and launchers left after the Israelis are done with their systematic targeting.

Of course, that could start a cycle of escalation: If Americans are killed, or even injured, Mr. Trump will be under pressure to exact revenge.

“Subcontracting the Fordo job would put the United States in Iran’s sights,” Daniel C. Kurtzer, a former U.S. ambassador to Israel, and Steven N. Simon, a veteran of the National Security Council, wrote in Foreign Affairs on Wednesday. “Iran would almost certainly retaliate by killing American civilians. That, in turn, would compel the United States to reciprocate.”

“Soon enough,” they continued, “the only targets left for Washington to hit would be the Iranian regime’s leaders, and the United States would again go into the regime-change business — a business in which exceedingly few Americans want to be involved any longer.”

The reaction could take other forms. Iran is skilled at terrorism, and reacted to the U.S.-Israeli cyber attack on its nuclear program 15 years ago by building a fearsome cyber corps, not as stealthy as China’s or as bold as Russia’s, but capable of considerable damage. And it has plenty of short-range missiles left to attack oil tankers, making transit in the Persian Gulf too risky.

The last thing the White House wants to do is air these risks in public. Democrats are calling for a congressional role, but they have no power to compel it. “Given the potential for escalation, we must be brought into this decision,” Senator Adam B. Schiff of California, one of Mr. Trump’s political rivals, said on CNN on Wednesday. “Bombing Fordo would be an offensive activity.”

And like most offensive activities, there are longer-term perils, beyond the cycle of attack and retaliation.

Already, the message of these past five days, as interpreted by Iranian leaders or others with nuclear skill, may well be that they should have raced for a bomb earlier, and more stealthily. That was what North Korea did, and it has now ended up with 60 or more nuclear weapons, despite years of American diplomacy and sabotage to stop it. It is a big enough arsenal to assure that its adversaries, South Korea and the United States, would think twice about conducting the kind of operation that Israel executed against Iran.

And history suggests that nuclear programs can be bombed, but not eliminated.

“Nuclear weapons can be stopped through force — the Syrian program is a good example,’’ said Gary Samore, who was the Obama administration’s coordinator for weapons of mass destruction when the existence of the Fordo plant was made public. (It was discovered toward the end of the Bush administration.)

And in Iraq, after the Israelis bombed the Osirak reactor in 1981, to keep Saddam Hussein from getting the fuel for a bomb, the Iraqis “reacted by building a huge, secret program” that went undetected until after the Gulf War in 1991, Mr. Samore said. That was such an embarrassment to American intelligence agencies that more than a decade later they wildly overestimated his ability to do it again, contributing to the second failure — and leading the United States into the Iraq war.

But Mr. Samore added: “I can’t think of a case where air power alone was sufficient to end a program.”

That is an important consideration for Mr. Trump. He must decide in the next few days whether Israel’s attacks on Iran’s Natanz enrichment facility, and its bombing of workshops where new centrifuges are made and laboratories where weapons research may have been taking place, are sufficient to set back the Iranian program.

In short, he must decide whether it is worth the huge risk of direct American involvement for whatever gain would come from destroying Fordo with American pilots, American warplanes and American weapons.

But he also doesn’t want to be accused of missing the chance to set the Iranians back by years. “If this war ends and this Fordo is left intact,” said Mr. Samore, now a professor at Brandeis University, “then it wouldn’t take long to get this going again.”

Mr. Trump has not weighed these questions in public, and it is always hard to know how he is assessing the evidence. He bristled the other day, on Air Force One, when a reporter noted to him that his own director of national intelligence, Tulsi Gabbard, had testified in Congress just a few months ago that Iran had made no decision to produce a bomb, even if its fuel production had surged.

He insisted that there wasn’t much time left — though he cited no evidence to contradict his own intelligence chief.

“Don’t forget, we haven’t been fighting,” Mr. Trump said Wednesday in the Oval Office. “We add a certain amount of genius to everything, but we haven’t been fighting at all. Israel’s done a very good job today.”

Then, muddying the waters anew, he turned to his signature phrase: “But we’ll see what happens.”