The Doctrine Behind the Threat

Israel's approach to the Iranian nuclear threat is grounded in a strategic doctrine that predates the current government and has been articulated consistently across administrations that disagreed on almost every other policy question. The doctrine holds that Israel will not permit a hostile state with declared intent to destroy it to acquire nuclear weapons. This is not a negotiating position. It is a stated existential commitment that Israeli governments have treated as a constraint on their own decision-making, not merely as a signal to adversaries.

The practical implication of this doctrine is that Israel has maintained a standing requirement to develop and sustain the capability to strike Iran's nuclear infrastructure, regardless of whether the diplomatic track is open or closed, regardless of US preferences, and regardless of the regional consequences. This requirement has shaped Israeli defence procurement, force structure decisions, and operational planning for over fifteen years.

What has changed in 2026 is not the doctrine. What has changed is the assessment of whether the diplomatic track can still prevent the outcome the doctrine is designed to preclude. Israeli policymakers who had previously argued that sanctions, sabotage, and diplomacy could buy sufficient time have progressively reached the conclusion that the time bought has been used by Iran to advance its program rather than by the international community to constrain it.

The Target Set

Any Israeli strike on Iran's nuclear program would focus on a relatively defined set of facilities that represent the critical nodes of the enrichment and weaponisation capability. Each target presents different challenges in terms of accessibility, hardening, and the consequence of incomplete destruction.

Natanz is the primary enrichment facility and the most important target. It houses the centrifuge cascades that produce the bulk of Iran's enriched uranium. The facility has underground halls that are hardened against conventional air attack, but the depth of the main halls is accessible to penetrating munitions of sufficient weight and precision. A successful strike on Natanz's enrichment halls would set back the enrichment program significantly, though Iran's centrifuge manufacturing capacity means that reconstitution is possible within a period of months to years rather than permanently.

Fordow is the most challenging target in the Iranian nuclear complex. Built inside a mountain in the Qom province, Fordow was specifically designed to survive air attack. Its depth is estimated at between 80 and 90 metres of solid rock, exceeding the penetration capability of most conventional munitions. Only the most specialised deep-penetrating munitions in the US arsenal, primarily the Massive Ordnance Penetrator at approximately 13,600 kilograms, are assessed as capable of potentially damaging it, and even these assessments carry significant uncertainty about whether a single strike would destroy the facility or merely damage it. Israel does not possess the Massive Ordnance Penetrator and would require US participation to credibly threaten Fordow.

Isfahan is the uranium conversion facility that processes uranium before enrichment. It is a softer target than Natanz or Fordow and more accessible to Israeli air power without specialised deep-penetrating munitions. Destroying Isfahan would disrupt the fuel cycle upstream of enrichment, but Iran's documented technical knowledge and industrial capacity make reconstruction feasible, though time-consuming.

Associated targets would include ballistic missile storage and launch facilities, air defence radars and command nodes along the ingress and egress routes, and potentially the research and development infrastructure associated with weaponisation. The scope of strikes on non-nuclear targets determines whether the operation is understood as a surgical nuclear intervention or as a broader military campaign against Iranian capabilities.

Israeli Strike Capabilities

Israel's primary platform for a long-range strike against Iran is the F-35I Adir, the Israeli variant of the Lockheed Martin F-35A with Israeli-specific modifications. The F-35I combines low-observable characteristics with extended range and weapons integration that makes it significantly more capable for this mission profile than Israel's previous strike platforms.

The distance from Israeli airbases to Iranian nuclear sites is approximately 1,500 to 1,700 kilometres depending on routing. This is within the F-35I's operational range with conformal fuel tanks, though not comfortably so. The routing question is itself strategically significant. Overflying Jordan and Saudi Arabia requires political cooperation or tolerance from those governments. Routing north over Turkey and then east is politically unavailable. Southern routing over the Red Sea and Arabian Peninsula is longer but politically more feasible given Gulf Arab preferences on the Iran question.

Aerial refuelling is the critical enabler for extended range operations. Israel's KC-46 tanker acquisition and its existing tanker fleet provide this capability, though the number of refuelling sorties required for a sustained campaign creates operational exposure for the tanker aircraft themselves. Iran's air defence coverage along likely approach routes determines how much this exposure matters in practice.

Israel has also invested substantially in long-range precision-guided munitions, including standoff weapons that can be deployed from outside Iranian air defence coverage. These weapons extend the range at which Israeli aircraft can engage targets without penetrating the most heavily defended zones, but they also carry smaller warheads than the direct-attack munitions required for hardened targets.

The Role of US Assets

The single most consequential variable in any Israeli strike scenario is the level of US participation. This variable has three meaningful states: active US co-belligerency in which American aircraft and munitions directly participate in strikes; active US support in which the United States provides refuelling, intelligence, and air defence assistance without conducting offensive operations; and US awareness with tacit acceptance in which Israel acts with prior communication to Washington but without formal American involvement.

Active US co-belligerency provides the only credible path to a strike on Fordow, given the requirement for the Massive Ordnance Penetrator and the B-2 platform required to deliver it. If Fordow is not seriously damaged, a strike that destroys Natanz and Isfahan leaves Iran with a surviving hardened enrichment capability that could reconstitute faster than the elements that were destroyed.

Active US support short of co-belligerency enhances the survivability and effectiveness of Israeli strike packages through suppression of Iranian air defences, tanker access, and real-time intelligence. It also changes the political character of the operation in ways that affect Iranian retaliation calculus, Gulf Arab positioning, and European diplomatic response.

US awareness with tacit acceptance preserves the most political deniability for Washington but provides the least operational benefit. It also creates the awkward situation in which US forces in the region face Iranian retaliation for Israeli actions while the US government has not formally committed to the conflict.

The Day After Problem

Military planning for a strike on Iran's nuclear program is, in an important sense, the easier part of the problem. The harder part is what happens next.

The strongest argument against a strike is not that it would fail to damage Iran's nuclear program. A well-executed strike with US participation would set the program back by years. The argument against is that it would not end the program. Iran would reconstitute, faster with domestic political justification provided by the attack, with a hardened determination not to be in the same position of vulnerability again, and with a programme that had demonstrated its survival despite the most capable air forces in the world attempting to destroy it. The deterrence logic that a strike provides temporary delay would need to be revisited within a decade or less.

The regional consequences of a strike are similarly double-edged. Iranian retaliation against Israel, US forces, and Gulf infrastructure would be costly. The political cost to the region's governments of being seen to have supported or tolerated a strike against a Muslim-majority country would create pressures on their domestic political systems. The disruption to energy markets discussed elsewhere would impose economic costs that fall disproportionately on developing economies that are not party to the conflict.

Against these costs, proponents of action argue that a nuclear-armed Iran presents risks that are categorically worse: a fundamental shift in the regional balance of power, the removal of any credible Israeli conventional deterrent against Iranian-backed attacks, and the near-certainty of nuclear proliferation cascading to Saudi Arabia and Turkey as regional powers that cannot accept unilateral Iranian nuclear status.

This is the argument that Israeli planners have been making internally for years. What has changed in 2026 is that more of the people who heard it are now persuaded that the costs of action are lower than the costs of continued inaction. That persuasion, more than any capability development, is what has brought the region to its current position.