Smoke billows after an explosion in Tehran, Iran, following Israeli strikes on June 13, 2025. The Middle East awoke to a frightening new reality after Israel’s reported strike on Iran’s capital yesterday, raising the unthinkable question: could this conflict escalate into a nuclear war? Explosions rocked Tehran in the early hours, as Israeli warplanes hit multiple targets including alleged nuclear sites. Iran’s Supreme Leader Ayatollah Ali Khamenei responded by branding the attack a “wicked crime” and vowing “severe punishment” in retaliation. With both nations exchanging fierce rhetoric and Iran launching waves of drones in response, fears are mounting that a spiral of violence might cross the ultimate red line – the use of nuclear weapons.

Why Nuclear Fears Are Rising

Israel’s overnight strikes on Tehran marked a dramatic escalation in their long-simmering conflict. Israeli Prime Minister Benjamin Netanyahu described the operation – which reportedly killed top Iranian generals and nuclear scientists – as a preemptive effort to cripple Iran’s nuclear program and protect Israel’s very existence. Iran, in turn, has placed its military on high alert and signaled that missile and drone retaliation will continue. This sudden eruption of open warfare between a nuclear-armed state (Israel) and a state suspected of nuclear ambitions (Iran) has fueled international alarm. Global leaders from Washington to Brussels are urgently appealing for restraint and diplomacy, warning that any miscalculation could have catastrophic consequences.

Even before these strikes, tensions over Iran’s nuclear advances were reaching a boiling point. Just one day prior, the UN’s nuclear watchdog formally censured Iran for failing to cooperate with inspectors – the first such rebuke in two decades. Tehran responded defiantly by announcing plans to open a third uranium enrichment site and deploy more advanced centrifuges, accelerating a program that Western intelligence says has already amassed enough high-enriched uranium for several bombs. Israel has repeatedly warned it will not allow Iran to acquire nuclear weapons and would act “by force if necessary” to stop it. That warning was made real in the past 24 hours, as Israel’s air force (with over 200 jets in action) struck Iran’s critical nuclear infrastructure, including the sprawling Natanz enrichment facility.

The specter of nuclear conflict is no longer theoretical. As European Commission President Ursula von der Leyen put it, the situation is “deeply alarming” – a sentiment echoed by NATO and UN officials urging maximum caution. For the first time in decades, observers are openly contemplating scenarios in which either Israel or Iran, under extreme duress, might resort to their most devastating weapons. Below, we examine what developments might push Israel to use a nuclear weapon, and under what circumstances Iran might deploy a nuclear device – if it has one – either directly or via allied groups.

What Could Push Israel to Use Nuclear Weapons?

Israel is widely understood to possess a substantial nuclear arsenal (albeit undeclared), developed as its ultimate deterrent against existential threats. In its 75-year history, Israel has never officially confirmed having nuclear warheads, much less indicated any intent to use them offensively. The thought of breaking the nuclear taboo weighs heavily: doing so would shatter nearly 80 years of non-use since WWII and invite global condemnation. Yet Israeli strategists have also long maintained that in a scenario where the nation’s survival is at stake, “all options are on the table.” This implies that extreme circumstances could trigger Israel’s so-called “Samson Option” – a last-resort nuclear response if the country were in danger of annihilation.

Potential triggers for Israeli nuclear use generally fall into a few dire scenarios:

• Existential Threat to National Survival: If Israel’s leadership believed the nation faced imminent destruction – for example, if Iran launched a nuclear strike or another weapon of mass destruction against Israeli cities – it could compel Israel to consider a nuclear retaliation as an act of national survival. Israeli officials have explicitly framed Iran’s acquisition of nuclear arms as a “clear and present danger to Israel’s very survival”. In practice, an Iranian nuclear strike (should Iran ever obtain that capability) would almost certainly cross Israel’s red line and provoke a nuclear counterstrike aimed at neutralizing Iran’s ability to wage war. Analysts note that any Iranian use of a nuclear bomb would be essentially suicidal, as it would “assure [Iran’s] own demise” by triggering an overwhelming Israeli (and possibly American) nuclear response. In short, Israel’s nuclear weapons are the final insurance against being wiped off the map.
• Overwhelming Missile or Drone Barrages: Short of an actual nuke, Israel could be pushed to the brink if it suffered massive conventional attacks that threaten to overpower its defenses and devastate its population. Iran and its proxies (such as Hezbollah in Lebanon or militias in Syria and Iraq) together field huge arsenals of missiles and armed drones. In the current conflict, Iran already launched over 100 armed drones toward Israel in retaliation for the Tehran strikes. Israeli air defenses intercepted those before they reached their targets, and civilians were able to emerge from bomb shelters soon after. But military planners worry about a worst-case scenario: a coordinated multi-front missile barrage from Iran and its proxies that could saturate Israel’s Iron Dome and Arrow defense systems. If hundreds of rockets rained down on Tel Aviv, Haifa, and Jerusalem causing mass casualties or crippling infrastructure, Israeli leaders might conclude that only the shock of a nuclear strike on the launch sources could halt the onslaught. Already, Israel has declared a nationwide emergency “special situation” and prepared bomb shelters in anticipation of heavy Iranian retaliation. This underscores that Israeli authorities perceive the threat of large-scale missile attacks as a matter of national survival. While Israel would likely exhaust every conventional option (and call on international support) before considering a nuclear response, an overwhelming attack that left Israel’s cities burning or its defenses collapsing would significantly raise the pressure to use its most powerful deterrent.
• Loss of Strategic Assets or Leadership: Another dire scenario would be if Iran (or its allies) managed to destroy critical Israeli strategic assets or decapitate its leadership. For instance, a direct hit on Israel’s principal nuclear reactor or weapons facilities, or the assassination of top Israeli leaders in wartime, could be seen in Israel as an attempt to fatally cripple its security. Iranian forces have already proven bold by striking deep into Israeli territory via proxies (and, in this week’s case, absorbing an unprecedented strike on their own capital). If Iran were to somehow strike the Israeli nuclear complex at Dimona or eliminate a significant portion of the Israel Defense Forces’ command structure, the resulting desperation could breach the nuclear threshold. Israel might resort to a nuclear strike either as a form of “Armageddon insurance” – ensuring its adversary is destroyed as well – or to prevent further attacks when conventional means are insufficient. Israeli nuclear doctrine is opaque, but the implicit message for decades has been that Israel will not go down without using every tool at its disposal. As one former Israeli defense official put it, Israel’s enemies must always remember that “if Israel is existentially threatened, what use are subtlety or restraint?”

It is important to emphasize that Israel would see nuclear use as a last resort, only after all other options and international support were exhausted. The current conflict, though severe, has not reached that threshold. Israel’s initial airstrikes, while extraordinary in scale, were carried out with conventional precision weapons. Moreover, Israel’s allies – notably the United States – are strongly opposed to any nuclear escalation. Washington has reaffirmed Israel’s right to self-defense but also distanced itself from the operation, signaling that it “was not involved” in the Tehran strikes and warned Iran against hitting U.S. targets. President Donald Trump (now in his second term) reportedly was informed in advance of Israel’s action and has publicly urged Israel to focus on forcing Iran back to the negotiating table rather than expanding the war. In other words, Israel is under heavy diplomatic pressure to keep the conflict from spiraling out of control. Barring an existential emergency, it would not want to risk becoming the first country since 1945 to employ nuclear weapons in anger – a move that could make it a pariah and invite unpredictable retaliation.

Under What Circumstances Might Iran Use a Nuclear Weapon?

Iran’s official position has long been that it does not seek nuclear weapons and that such arms are forbidden by a supreme leader’s fatwa. As recently as April 2024, Iranian officials insisted “nuclear weapons have no place in our doctrine”. Nevertheless, Iran has steadily expanded the capacity and know-how that could produce a bomb, all while skirting the line of its international commitments. Western intelligence assessments as of this week continue to assert that Iran has not yet built an actual nuclear warhead. Iran has enriched uranium up to 60% purity and amassed enough fissile material that, if further enriched to weapons-grade, could yield multiple nuclear devices. In other words, Tehran is considered a “threshold nuclear state,” technically capable of making a bomb in short order if its leaders make the fateful decision.

Some observers have speculated that Iran may have already acquired at least a crude nuclear capability, perhaps through clandestine purchases of fissile material on the black market. In fact, as far back as 2001, the CIA cautioned that it “could not rule out the possibility that Iran has already acquired a nuclear weapon capability, if it has succeeded in secretly procuring fissile material abroad.” There have been periodic rumors and unconfirmed reports over the years suggesting Iran obtained nuclear components or even an intact warhead from foreign sources, though no hard evidence has ever surfaced. These claims remain unproven – U.S. and Israeli officials publicly maintain that Iran does not possess an operational nuclear weapon at this time. Still, the very fact that such claims persist underscores the deep uncertainty surrounding Iran’s program. The opacity of Iran’s activities, combined with its recent move to restrict IAEA monitoring, means the world might not immediately know if Tehran crosses the nuclear threshold.

Assuming Iran either has or someday develops a nuclear weapon, under what circumstances might it actually use one? For Tehran, the calculus would be daunting. Any first use of a nuclear weapon by Iran would almost certainly invite devastating retaliation, given Israel’s second-strike capability and the United States’ explicit warnings of a “strong response” if Iran targets American interests. Essentially, Iran would be signing its own death warrant by launching a nuclear strike – a reality not lost on Iranian strategists. Therefore, most analysts believe Iran would consider deploying a nuclear weapon only in extremis, if the regime’s survival were hanging by a thread. Possible scenarios include:

• Regime or National Survival at Stake: If Iranian leaders became convinced that an ongoing war was about to result in the collapse of their government or the occupation of Iran, they might resort to the last-ditch option of using a nuclear weapon in hopes of shocking their enemies into backing off. For instance, if an Israeli (or U.S.) conventional campaign were on the verge of decapitating Iran’s leadership or obliterating its military, Iran could see a nuclear detonation as a final means to avert defeat. This could take the form of a direct nuclear strike on an Israeli city or military base, aiming to cause unsustainable damage and force a ceasefire. However, Iran’s leadership is acutely aware that Israel has an undeclared but robust nuclear arsenal of its own. Any Iranian nuke launched at Israel would invite overwhelming retaliation that could annihilate Iran’s military and major cities. Thus, Tehran would likely weigh “assured destruction” in the balance – using a nuke might not save the regime at all, but rather ensure its end. The threshold for such a desperate move would therefore be extremely high, arguably only if Iran’s rulers felt they had nothing left to lose.
• Demonstration or Coercive Use: Short of an outright attack on a population center, Iran could conceivably employ a nuclear device in a more limited (but still perilous) way to try to coerce Israel and the world. This might involve a nuclear test or high-altitude detonation as a demonstration, or an explosion in a sparsely populated area to signal that Iran now has the bomb and is willing to use it. Such a demonstration could be intended to deter further aggression against Iran by showcasing its newfound capability. Some analysts point out that if Iran secretly built one or two crude nuclear weapons, it might initially use one in a demonstrative manner – hoping the mere fact of exploding a nuke would make Israel and its allies think twice about continuing hostilities. However, even a demonstration blast carries enormous risks: it could be misinterpreted as an attack, or prompt Israel to pre-emptively strike any other suspected Iranian nuclear assets before a second device could be used. Notably, Iran’s recent rhetoric has grown more bellicose; Iranian officials have started musing about the “possible need” for nuclear weapons, a stark shift that worries nonproliferation experts. Any actual nuclear detonation by Iran, even as a warning shot, would cross a threshold the international community has vowed never to allow.
• Use via Proxy or Terrorist Delivery: A particularly nightmarish scenario often discussed in security circles is that Iran might try to deploy a nuclear weapon covertly through one of its proxy militant groups or by covert means, rather than via an overt missile launch. Iran has well-established networks with organizations like Hezbollah (in Lebanon) and has been accused in the past of covert attacks abroad using the Revolutionary Guard or allied militias. If Iran possessed a small nuclear device, it is conceivable (though highly risky) that it could attempt to smuggle it to a target – for example, delivering it via a shipping container or handing it off to a terrorist cell to detonate in an Israeli city. The logic (from Iran’s perspective) would be to inflict a catastrophic blow while muddying attribution, possibly hoping to avoid direct blame or to claim a rogue actor was responsible. However, detonating a nuclear bomb anywhere would produce forensic evidence and global shock that would almost certainly point back to Tehran. The response from Israel and likely the United States would be swift and devastating once culpability was established. In essence, a proxy-use scenario is widely considered beyond the pale because it offers Iran little shield from the consequences. Still, Western intelligence remains watchful of any signs that Iran’s regime might transfer fissile material or bomb designs to extremist groups. That concern is part of why Israel and the U.S. have been so adamant about preventing Iran from ever obtaining a nuclear weapon in the first place. It is also worth noting that Iran’s proxies can already cause havoc with conventional means (as seen with Hezbollah’s huge rocket arsenal), and they do so without Tehran resorting to nuclear options. This suggests Iran prefers to use its proxies for calibrated conventional attacks, not apocalyptic ones that would bring unbearable reprisals on Iran itself.

At present, Iran does not admit to having any nuclear weapons, and there is no confirmation that it has crossed that threshold. The scenarios above remain hypothetical. Iran’s immediate response to the Israeli airstrikes has been through conventional force – firing drones and likely preparing ballistic missile salvos – rather than any nuclear signal. Iran’s Supreme Leader Khamenei has promised harsh retribution for the deaths of his generals, but his statements stop short of referencing weapons of mass destruction. This indicates that, for now, Tehran intends to retaliate within the conventional realm (albeit fiercely). The international community has also moved quickly to contain the crisis: Iran has called for an emergency UN Security Council meeting to condemn Israel’s aggression, and countries like Russia and China (though not quoted in sources above) are undoubtedly pressuring behind the scenes for de-escalation, as a nuclear exchange would endanger the entire region and beyond.

Diplomatic Moves and Global Reactions to Avert Nuclear Escalation

With the specter of nuclear conflict looming, world powers are scrambling to prevent the Israel-Iran war from reaching that point. Global reaction over the last two days has been a mix of condemnation, concern, and calls for urgent diplomacy. The United States, while supporting its Israeli ally’s right to self-defense, pointedly noted it did not endorse or participate in the strike on Tehran. Washington has begun quietly repositioning military assets in the region as a precaution (the U.S. Navy and Air Force in the Gulf are on alert), and it has evacuated non-essential personnel from diplomatic missions in sensitive Middle East locations. President Trump has taken a two-pronged public stance: praising Israel’s resolve in neutralizing a threat, but simultaneously urging Iran to return to negotiations “before it’s too late.” In a White House address today, Trump warned that Israel “will strike for as many days as it takes” and hinted that more Israeli attacks could be coming if Iran doesn’t stand down. His message to Tehran was blunt – “No more death, no more destruction. Make a deal.” – suggesting that the door to a diplomatic off-ramp is still open if Iran ceases escalation.

European and other international leaders have been even more direct in urging restraint. EU officials termed the escalation “deeply alarming” and stressed that “there is no other solution than a diplomatic one” to the Iran-Israel standoff. Britain’s Prime Minister, Keir Starmer, publicly clarified that the UK’s Royal Air Force is not involved and called on “all parties to step back and reduce tensions urgently.” Even countries historically sympathetic to Iran, like Russia and China, have strategic reasons to prevent a nuclear conflict and are likely counseling Tehran to avoid any drastic measures (though official statements from Moscow/Beijing were not available at the time of writing). Notably, the United Nations Secretary-General has called for “maximum restraint” and warned that any targeting of nuclear facilities – in an ongoing conflict or otherwise – carries extreme dangers. The head of the International Atomic Energy Agency, Rafael Grossi, offered to send experts to assess any damage at Iran’s nuclear sites, underscoring global concern about nuclear safety and the potential for an environmental disaster if sites like Natanz or Fordow are bombed.

For now, both Israel and Iran insist they do not want a wider war, especially one involving weapons of mass destruction. Israel’s defense minister announced the country has activated its Arrow and David’s Sling missile defense systems and is confident it can shoot down incoming Iranian missiles, reassuring the Israeli public while also implicitly warning Iran that a missile attack might fail. Iran’s leadership, while angry and poised for revenge, knows that using a nuclear weapon (if it had one) would turn virtually the entire world against it and likely spell the end of the Islamic Republic. Tehran has therefore focused on rallying sympathetic nations diplomatically and using conventional military means for retaliation. Already, Iranian media tout “furious strikes” against Israeli targets – such as today’s drone barrage – as proof that Iran can respond forcefully without nukes.

The coming days will be crucial in determining if the crisis abates or escalates. Iran’s next moves are being watched closely: will it unleash its arsenal of medium-range ballistic missiles on Israeli cities, which could sharply raise the death toll and pressure Israel into considering drastic options? Or will it limit its response to calibrated strikes (perhaps via proxies like Hezbollah launching rockets from Lebanon or militias firing at U.S. bases in Iraq) to avoid provoking Israel’s full wrath? Each side is also doubtless assessing the other’s red lines. Israel has made clear that any sign of Iran preparing a nuclear device for use would be unacceptable – and Israel might take preemptive action again, perhaps even more forcefully, if it detected such preparations. Iran, for its part, likely views any direct threat to the survival of its regime (for example, an attempt to kill Khamenei or collapse the Iranian state) as a red line that could trigger extreme reactions.

International mediators are working overtime to inject pauses in the hostilities. Switzerland and Oman – countries that have brokered Iran-West communications before – are rumored to be conveying messages between Jerusalem, Tehran, and Washington. France’s president, Emmanuel Macron, convened a special defense council and has been in contact with both sides to offer Paris’s good offices for de-escalation talks. Oil prices have spiked 7–8% on fear of a broader war disrupting Gulf oil lanes, adding economic pressure on all parties to find a resolution. There are also reports of quiet back-channel talks via the UAE or Qatar, exploring a face-saving way for Iran to claim victory and de-escalate – possibly in exchange for some easing of sanctions or a new regional security dialogue. Whether these diplomatic efforts gain traction may hinge on what happens on the ground in the immediate term.

A High-Stakes Standoff with Uncertain Outcomes

As things stand, the war between Israel and Iran remains conventional – intense and highly dangerous, but still limited to non-nuclear weaponry. Both nations know that crossing the nuclear threshold would be a point of no return, likely drawing both into a mutual annihilation scenario. That said, the events of the last 48 hours have brought them closer to that threshold than ever before. Israel’s bold strike inside Tehran and Iran’s fiery promises of vengeance have created a volatile situation where miscalculation or desperation could rapidly escalate the conflict. Analysts worry most about a fast chain of escalation: for example, if Iranian missiles killed a large number of Israeli civilians, Israel might feel compelled to strike Iranian soil even harder; if Israel’s conventional strikes began to topple Iran’s strategic capabilities, Iran might reach for any “equalizer” it has left. In this fraught atmosphere, the risk of nuclear brinkmanship is at its highest in decades.

Nevertheless, there are also powerful incentives to step back from the brink. Israel has delivered a serious blow to Iran’s nuclear and military leadership (eliminating IRGC Commander Gen. Hossein Salami and others), and it may judge that it has reestablished deterrence for now. Iran, while enraged, might calculate that a prolonged war with Israel (and by extension the U.S.) would jeopardize the regime’s very survival – a risk that outweighs the desire for immediate revenge. International actors, including the U.S., EU, Russia, and China, are largely united in not wanting a nuclear calamity to erupt. This global scrutiny could restrain the combatants; even Israel, which acted unilaterally, is aware that any hint of preparing its nuclear forces would trigger global panic and a breakdown of support from its allies.

In sum, what would it take for this war to go nuclear? – nothing short of an extreme collapse of restraint on either side. For Israel, that means a scenario where its back is against the wall, facing destruction or a nuclear attack, leaving it no choice but to unleash its atomic arsenal. For Iran, it means acquiring a usable nuclear weapon and deciding that only an atomic strike can save it from defeat – effectively a martyrdom operation for the regime. These scenarios are possible in theory, but both remain highly unlikely if cooler heads prevail. The tragedy, of course, is that wars often produce chaos and emotion that defy cool calculation. The world can only watch with bated breath and hope that, amid the smoke and fury of this conflict, reason and caution will carry the day. International diplomacy in the coming hours and days is squarely aimed at ensuring the Israel-Iran war does not become the world’s first nuclear exchange of the 21st century. As one NATO official warned, “even a single misstep could plunge the region into a full-scale war” – and once nuclear weapons enter the equation, all bets are off.