Yes the attack delayed the nukes

The twelve days war did set back significantly Iran’s nuclear programs- but not mainly due to its impacts on its nuclear sites

In the aftermath of the Israeli and U.S. preemptive attack on Iran, increasingly known as the twelve day war, a heated debate has emerged on how much did the Israeli, and especially the U.S. aerial attacks, actually set back the Iranian nuclear program. The focus has naturally been on how much damage Iranian nuclear facilities have suffered, with conflicting reports by various U.S. and Israeli sources as well as some usual dosages of Trump Administration puffery about the U.S. attack. This debate has commenced with the assumption by many scholars and experts that such an attack may incentivize Iran to redouble on its nuclear program in secret and go for a nuclear breakout very soon. This is especially seen as likely in the immediate future if some of the 400 kilogram stockpile of 60% enriched Uranium held by Iran prior to the attack had been smuggled out from Iranian nuclear facilities before the bombings or can be eventually recovered by it from the rubble.

The author does not deny that the twelve day war may lead to an increased desire by the Iranian government to produce and test a nuclear bomb. After some such historical cases of preemptive attacks on nuclear programs, such as the Israeli attack on Iraq’s nuclear facilities in 1981, the attacked government did resume its nuclear program and made significant progress towards a nuclear bomb. Likewise, I accept the claims of some proliferation experts that the residual Iranian nuclear capabilities, especially the said enriched Uranium, may enable Iran to resume in the narrow technical sense its nuclear program quite quickly.

What this debate is so far failing to take into account however is the wider military context and possibilities, beyond the exact level of damage to the nuclear facilities, that this war has left Iran in. The attack introduced a major plausible obstacle to Iran keeping the nuclear capabilities it gains that it needs to prepare for before trying for a nuclear breakout- a future Israeli (or U.S.) strike on Iran’s newly tested bomb or about to be tested bomb. Furthermore, the Israeli (and U.S.) attack did not just cause some damage to Iran’s nuclear program facilities as say the Israeli military attack on Iraqi nuclear program in 1981. In this case the Israeli attacks had much wider impacts- they also caused severe damage to key Iranian conventional capabilities and exposed to the Iranian leadership how deeply compromised Iran’s security establishment is by the Israeli Mossad- things needed for Iranian preparations against such a future preventive strike if they make a postwar go at a nuclear bomb. When those factors, not directly related to the physical damage to the nuclear program, are also taken into account it is clear that, assuming at least some significant damage to Iran’s nuclear facilities and breakout capacity (as even the more bearish estimates agree to have happened), that Iran’s ability to breakout to a nuclear weapon has been delayed by at least a few years.

To clarify, this analysis isn’t implying in any way, shape, or form that the author believes that this military strike was the best feasible option for dealing with the Iranian nuclear program. There were other, better peaceful roads not taken in the past that could have plausibly achieved more permanent solutions to the Iranian nuclear program and other problems with Iranian foreign policy without the significant collateral costs of this war- such as a good faith attempt by the first Trump administration to fix the issues with the JCPOA rather then leaving it in a fit of pique in 2018. Nor should this analysis be seen as implying support for any such future strikes in Iran (or elsewhere), given their obvious wider collateral costs and the usual availability of other peaceful options. Peace should be given a chance. With those key qualifiers noted, the twelve day war did nevertheless achieve a significant delay in the Iranian nuclear program, a delay that will be hopefully leveraged by policymakers for a more peaceful and sustainable solution to this problem.

The ignored wider effects of the twelve day war on Iran nuclear breakout ability

When a postwar Iranian break for the bomb has been discussed thus far it assumes implicitly that all Iran needs to do after the war in order to gain nuclear capabilities, and credible nuclear deterrence against Israel and the west, is to successfully test a nuclear device once. That assumption is based on the record of other countries nuclear programs where such a test was sufficient. However, this implicit assumption does not hold in the Iranian case after the twelve day war. The Israeli (and U.S.) preventive attack indicates to Iran that there are powerful actors that see the possibility of it holding a nuke as highly threatening who have the willingness and ability to attack its nuclear program if they detect an Iranian attempt to make a run for a nuclear bomb- and have a good chance of scuttling it prior to the test if they do.

This is a key shift from the prewar situation. Before the war started the Iranian government clearly thought, as its behavior in early 2025 in various ways indicated, that such a preventive attack by Israel or other countries was very unlikely to happen. Many outside observers (including the author) shared this belief given the expected costs to Israel and/or other countries of such an attack. With Israel conducting a preventive attack in practice with far lower immediate costs to itself then many anticipated while causing some damage to Iran’s nuclear programs, and gaining some U.S. defensive support and even offensive military assistance regarding one set of hard to attack nuclear targets, no Iranian leader could not take the possibility of another preventive attack as a highly plausible scenario in case Iran makes a future run for the nuclear bomb.

Even if Iran succeeds in testing the bomb without detection (or attack) by Israel or another country that is not signify the end of the possibility of a preventive attack in Iran’s current circumstances. In the near future, if Iran makes a run for the bomb, it is highly unlikely to have more then a handful of other nuclear bombs at the point of testing it. For example, even if all of the Iranian prewar stash of 400 kilograms of high enriched Uranium was safely hidden away by the Iranian government before the Israeli and U.S. attacks, it has been estimated that it would be enough for no more then 2-10 nuclear weapons, depending on the exact bomb designed used. In other words, on their own, Iran’s post test new nuclear capabilities would be unlikely to be perceived as survivable of an attack by Israel and perhaps other countries. Furthermore, with Iran and Israel separated by more then a thousand kilometers from each other (and far more in the case of other western countries) the immediate post test ability of Iran to deploy the other nukes it just produced against Israel or other western countries would not be seen as automatic or obvious. In the post twelve day war world, a successful Iranian nuclear test in the near future could therefore plausibly lead to another Israeli (or other country’s) preventive attack designed to eliminate Iran’s new nuclear abilities before Iran has the ability to deploy them against them or other countries.

Iran of course can prepare, prior to starting a run for a bomb, in ways that would enable it prevent or deter another preventive attack before or after a test occurs- and/or make its ability to immediately use its nukes post test as credible. However, all the actions it would need to do for this purpose would be time consuming and quite economically costly- on top of the time and economic costs of making the run for the nuclear bomb. This means that the attack, regardless of how much it set back exactly Iran’s nuclear program, has already imposed on Iran significant delays in being able to make a post attack run for a bomb if it chooses to do so.

In other words Iran would need, before making a future run for a bomb, the following actions regarding the Iranian state and its non nuclear military capabilities.

First, the Israeli attacks revealed how heavily compromised Iran’s military and political leadership is to Israeli espionage. Given Israel’s prewar efforts to sabotage Iran’s nuclear program and the 2024 assassination of Hamas leader Ismail Haniyeh while on a visit to Teheran, the Iranian leadership was obviously well aware even before the twelve day war that the Mossad had some ability to infiltrate its military establishment and nuclear program and had some intelligence assets there. However the war showed far greater Israeli espionage and sabotage capabilities with Israel, among other thus far known operations, successfully decapitating much of Iran’s senior military establishment at the start of the attacks in a targeted aerial bombing while at a secret meeting, running massive sabotage networks inside Iran able to generate dozens of major drone attacks on various targets to accompany the aerial bombings by Israeli jets, and killing more then a dozen senior Iranian nuclear scientists in various targeted attacks.

That record indicates an obvious risk to the Iranian leadership that any future attempt to make a run for a nuclear bomb will be detected by Israel shortly afterwards and be quickly eliminated in some covert or overt manner. The Iranian leadership is clearly aware of that and already in full spy hunting mode with Iran, for example, executing three alleged Israeli spies in the last few days and arresting hundreds more on espionage suspicions. However, even at the best of times spy hunting is a difficult and time-consuming process that can take years to successfully conduct. It took the U.S. government, for example, eight years to catch a single Russian mole in the CIA (Aldrich Ames) from when its existence was first seriously suspected. Iran almost certainly needs to remove a large number of such moles throughout various government and military organs while recovering from the war. Iran also needs to identify and block any possible digital avenues through which such Israeli spying happened as well. It is likely to take the Iranian government at least a few years of such careful efforts until the Iranian leadership will feel that it had sufficiently reduced the Israeli intelligence penetration of its military and political establishment that it can theoretically make such a run for a nuclear bomb without Israel knowing about it shortly afterwards.

Secondly, Iran will need to rebuild its anti aircraft systems. The Israeli attack led to the quick destruction of most of Iran’s anti-aircraft systems, enabling the Israeli air force to establish air superiority over most of Iranian airspace throughout the twelve day war. That Israeli air superiority was the key factor that enabled Israel to conduct the extensive bombings that it did of various Iranian military and political facilities without losing a single manned aircraft and only four unmanned drones. It was also one key factor that enabled the U.S. air force bombing of Iran’s nuclear sites with the bunker busters by greatly reducing the risk of any participating U.S. aircraft being downed in the course of the attack.

To foil or deter a repeat Israeli preemptive attack during a nuclear breakout attempt, or shortly afterwards, Iran now needs accordingly to rebuild its destroyed anti-aircraft system and make it much better then before the twelve day war. That will not be an easy, quick, or cheap undertaking. For example, a single Russian S-400 anti-aircraft battery, the best Russian anti-aircraft battery available at present for export, a system believed to be good enough to pose a serious danger of shooting down modern western aircraft like the F-16s and F-35s Israel has, each costs 1.25 billion dollars- and Iran needs to replace most of the eighty of its anti-aircraft batteries destroyed by Israel during this war at the total cost of tens of billion dollars to merely go back to its prewar capabilities. Modern anti-aircraft defense systems are composed of multiple interlocking systems that need to work together to enable effective defense against modern aircraft-so the cost of replacing the destroyed anti aircraft missile batteries is only one part of what Iran needs in order to create a new effective anti aircraft system on the technical side. Iran also needs to train thousands of Iranian soldiers to use effectively the new systems after a large share of those running its prewar anti-aircraft system probably died during the war. Buying, building, and transporting the various components of this system and training Iranian soldiers to use them will take a few years for Iran to achieve.

Thirdly, Iran will need to develop in advance a way to deploy their nuclear weapon to make its potential use against other, non-contiguous countries credible. Given the possibility of an Israeli attack to eliminate, post test, its brand new nuclear abilities Iran will need to have a proven immediate ability to use its nukes against Israeli targets to deter it. There are two plausible ways for Iran to do so. One is to mount its nuclear weapons on a ballistic missile. The other is to have the ability to deploy it from an Iranian plane, as were the nuclear bombs the U.S. used in Hiroshima and Nagasaki in 1945.

Iran certainly has the ballistic missile capability to deploy a nuke and some of its ballistic missiles are believed to have been developed to carry such a nuclear payload in the future. While not as accurate as western missiles, their recent use in the war indicates that Iranian medium and long-range missiles also have sufficient accuracy to avoid hitting by mistake nearby Arab states and their populations, making their deployment with nukes against major Israeli population centers credible to Israel in theory. However, to mount a nuclear bomb on a missile requires the nuclear bomb mechanism to be significantly miniaturized. That is not an easy undertaking for states even after they have tested their first nuclear bomb and can regularly manufacture them. For example, North Korea after its first nuclear test in 2006 is believed to have spent at least a decade trying to achieve that and it remains unclear, nearly two decades later, whether it has achieved yet that ability in full. An Iran fresh after a nuclear test using the remnants of its postwar nuclear program is highly unlikely to have that capability in the near future after the test.

Alternatively, a deployment of a nuke through a plane does permit the use of larger, relatively crude nuclear bombs of the type Iran is likely to have right after a nuclear test in the near future. However, Iran would need for this purpose multiple squadrons of advanced modern combat planes it to be able to have plausible chance (and a credible deterrent threat) of getting though Israel’s formidable air force and anti-aircraft systems and dropping Iranian nuclear bombs on Israeli soil. Iran’s air force however is quite small and outdated, composed of planes that Iran under the Shah bought from the U.S. in the 1960s and 1970s that survived subsequent fighting in the Iran-Iraq war together with some 1980s Soviet aircraft. Many of those planes were furthermore destroyed during the twelve day war. In order to use a nuke in this manner Iran would need first to effectively build a whole new, up to date air force from scratch. This would be a quite expensive and time-consuming undertaking. For example, one Su-57, an advanced model of Russian fighter planes that Iran, accordingly to some prewar reports was seriously thinking of buying from Russia, costs around 35-40 million dollars per plane. 40-50 planes of this type, a reasonable ballpark estimate of the minimal number needed by Iran to plausibly face the Israeli air force in such a task, would therefore cost Iran billions of dollars. This of course is an underestimate that excludes other things Iran would probably need for this task, such as a refueling aircraft, to enable those Iranian planes surviving the fight with the Israeli army to return to Iran and to maintain its future nuclear deterrence against other states- or another chance at using its nukes in case the initial attempt failed and the plane(s) carrying the nuke were shot down before they could drop it. It takes three years for the Israeli air force to train its combat pilots- so Iran no doubt will need at least around that amount of time to create a new cadre of pilots plausibly able to fight toe to toe with Israel (or other western air forces) in that task.

Finally, to deter a future Israeli (and other countries) attack Iran will need to rebuild & further expand its mid and long-range ballistic missile abilities. According to Israeli media reports, one key factor in the Israeli calculus for launching the strikes on Iran was a belief that Iran was planning a crash program of building its stockpile of medium and long-range missiles to a number so high (around 11,000) that Israeli anti-missile systems, such as the Arrow, would be completely overwhelmed in case of an Iranian attack, even with outside assistance with interdiction efforts, leading to massive conventional destruction across Israel on par nearly of an outright Iranian nuclear attack.

That Israeli fear, combined with the recent Israeli degradation of the Hezbollah’s Iranian provided missile abilities, was clearly one factor, aside of any intel Israel may have had about Iran’s nuclear weapon plans, for the Israeli decision to begin this conflict. The twelve day war severely degraded Iran’s ballistic missiles capabilities. The Israeli air force destroyed two thirds of Iran’s medium and long-range missile launchers. The Israeli destruction of various Iranian missile bases, combined with Iran’s wartime use of its missiles against various Israeli targets, halved Iran’s existing stockpile to around 1000-1500 medium and long range missiles. Also, according to various media reports, Iran’s ballistic missile production factories were one key target of Israeli bombings during the war. It will take time until the dust will settle and a clear picture of how severely the Iranian ballistic missile and missile launchers manufacturing capabilities were degraded. However, one can safely assume, even based on regular prewar Iranian production abilities (of about 600 ballistic missiles per year), that it will take a few years for the Iranian government to build enough medium and long range ballistic missiles for it to believe that it has enough of them to credibly deter Israel from attacking it for this purpose.

Another source of delay- Iranian politics

Another likely source of delay in any nuclear policies are the likely upcoming Iranian political developments. The current supreme leader of Iran Khamenei is 86 years old. There is already some possible evidence that Khamenei has been sidelined from key decisions during the war. However, even if that is not the case, given his very advanced age he is likely in one manner or another to leave very soon the Iranian political stage. That means that much of Iranian politics in the near future, assuming a continuation of the current regime, will be consumed by the informal and formal selection processes of his successor. Any decision on Iran going for post war run for a nuclear bomb will accordingly be taken by Khamenei’s successor in likely consultation with other Iranian political actors.

It is unclear who will exactly succeed Khamenei. In the rather murky world of Iranian politics few people would hazard a guess as to who would exactly succeed him or what will be their exact policy preferences when it comes to the future of Iranian foreign policy. A more hawkish successor (or a weak leader effectively dominated by hawkish elements in the Iranian regime) is certainly a possibility as well as some scholars note.

However, regardless of the choice of exact successor to Khamenei, the upcoming succession will lead to a further delay in any possible attempt at nuclear breakout. First, any successor will need time to settle himself in office. Secondly, more importantly, an internal review of Iran’s foreign policy strategy and policies are very likely. Khamenei has been a key architect of the current Iranian nuclear and foreign policy. The developments since the October 7, 2023 attacks have already put into question one key part of Iranian foreign policy- the cultivation of various proxies throughout the Middle East from the Hezbollah, to the Hamas, to the Houthis. The twelve day war also puts into question the wisdom of Iran’s nuclear weapons policy. Accordingly, any future successor of Khamenei, regardless of their foreign policy preferences, will likely be unwilling to automatically continue his predecessors nuclear and foreign policies and will want to carefully review them first in order to determine what should be continued and what should not. Until these processes are concluded it is highly unlikely any Iranian successor to Khamenei, even a highly hawkish one, will take the highly risky step of preparing the ground for or an actual run for a nuclear bomb.

No deus ex machina route to an Iranian bomb

Of course someone reading this piece up to here would wonder about another possible Iranian route for the bomb- namely that the events of the war may lead a third country to simply give some nuclear bombs to Iran. For example, didn’t former Russian president Dmitry Medvedev hint in one his tweets during the war about Russia giving a nuclear weapon to Iran?

Medvedev however quickly walked back this implied threat once it received some international attention- and it is unlikely to have been made seriously by him. Such an act is moreover highly implausible. The eighty year history of nuclear proliferation has been heavily well studied by historians and scholars and there is no known case in which a nuclear weapon country gave a ready for use nuclear weapon to another country for use at its pleasure as other weapon systems are sometimes sold or given. At most nuclear weapon countries have been willing to provide equipment enabling another country to build one on its own a few years down the line or nuclear sharing agreements that enable the receiving country to use the nuke in some circumstances while retaining for the giving state some control over its use. There is a good reason for that- giving outright a nuclear weapon to Iran can make other countries see the nuke giver as responsible for any misuse of the weapon and the target of severe opprobrium, punishment, and sanctions if its eventually (mis)used.

Moreover, given Iran’s geopolitical situation it is highly unlikely to become the special eighty year exception to the rule. Iran’s strategic value to other nuclear weapon countries is limited. Iran is a medium sized country with limited conventional military abilities which is moreover quite impoverished by years of sanctions, corruption and economic mismanagement. Iran is indeed a significant oil producer but there are many other countries with similar production capabilities that can easily substitute for it. Iran can potentially shut down the straits of Hormuz- but only at the extremely high cost of shutting down most of its own oil exports (and its main source of income) making Iran’s actual ability to do so in practice limited to extreme emergencies. In the medium term, even this Iranian strategic value is declining as countries slowly transition away from fossil fuels. Russia also does not need anymore Iranian aid in producing drones for its own military needs. The Iranian defeat in the twelve day war, and the events post October 7 that decimated Iran’s various proxies, show the Iranian leadership’s whole foreign and national security policy of the last few decades to suffer from severe flaws. A country of limited strategic value shown recently to be prone to severe strategic miscalculations and incompetence, as well being heavily penetrated by the Mossad, is not exactly an appealing partner- especially for the unprecedented step of giving a nuclear weapon.

Furthermore, such an act by a nuclear weapon state would also immediately alienate Saudi Arabia and the Gulf states- which have also frequently expressed severe fears of an Iranian nuclear bomb. Those countries also happen to be quite friendly at present with Russia and many of the other nuclear weapon states that can in theory do that (such as Pakistan)- adding to the already high costs of such an act. Accordingly, Iran is extremely unlikely to gain a nuclear weapon through such a deus ex machina.

Conclusions

The current debate on the twelve day wars impact on the future of the Iranian nuclear program has so far focused on what was exactly harmed in the Iranian nuclear program as a result of the Israeli and U.S. bombings. As a result the debate has largely ignored thus far the other key way in which the war impacted the Iranian government ability to break out for a bomb- namely the time consuming and economically expensive things the Iranian government will need to do first on the non nuclear side- from hunting Mossad spies in Iran, to rebuilding Iran’s anti-aircraft and ballistic missile capabilities, to creating a plausible nuke delivery system before it starts a nuclear break out given the credible threat of a future Israeli (and/or U.S.) preventive strike when a postwar run for a nuke is started or right after an Iranian nuclear test. Accordingly, even if the bearish classified DIA estimate is fully accurate, and the twelve day war merely added when it came to the Iranian nuclear program only a few additional months to the Iranian nuclear breakout time, the other impacts of the Israeli (and U.S.) bombings have delayed a likely Iranian breakout by at least 3-5 years.

As noted, this overall optimistic analysis about the effects of the war on delaying an Iranian nuclear bomb should not be seen as an endorsement of such a preventive attack as the best option for dealing with such situations- let alone calling for more such strikes by any country in the future. Peaceful options should be strongly preferred for dealing with such situations. With that noted, this analysis indicates however that this particular war did however buy some valuable time for a peaceful solution. Policymakers should accordingly try to spend this time productively in order to create a negotiations process that will more permanently prevent the possibility of an Iranian nuclear bomb through peaceful means.