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The 2026 US-Iran War: A Six-Phase Assessment

Picture of Tahir Azad

Tahir Azad

Analysis Series

Analysis/0048/July/2026/London-Dialogue. 18 July 2026

The war that started on 28 February 2026 has become the defining strategic shock of the year. Its effects reach far beyond the theatre itself, with the contest over the Strait of Hormuz driving energy shortages, freight disruption and inflationary pressure across the global economy. The Trump administration appears to have anticipated neither the scale of Iran’s regional response nor the political durability of a state it expected to fracture. Even after the killing of Ali Khamenei and much of Iran’s senior leadership, Tehran has continued to fight. This assessment reads the conflict across six phases, judged not by the balance of firepower alone but by the two logics that now govern it: the survival of the Iranian regime and the political survival of the American presidency.

Figure 1. The Six Phases as an Escalation and De-escalation Arc. Phases 5 And 6 Are Projected Scenarios.

The Two Logics of Survival

The war is best understood as a collision between two survival imperatives rather than a straightforward test of military strength.

For Tehran, this is an existential struggle over control of the Iranian state. The Islamic Republic has framed the campaign as a war of national survival, and the mass mobilisation around Khamenei’s funeral suggested a level of public cohesion that Iraq, Libya and Syria never possessed at the point of external intervention. That cohesion is contested. The stated Israeli and American aim were regime change, premised on the judgement that the system was brittle, and the Congressional Research Service records episodes of popular unrest alongside the displays of loyalty. What is not in doubt is that the leadership has treated retreat as regime death and has fought accordingly.

Iran’s material strategy rests on three pillars. The first is its inventory of ballistic missiles and drones, which forms the core of its deterrent and its retaliatory reach across the region. The second is geography, above all its command of the northern shore of the Strait of Hormuz, through which roughly a quarter of the world’s seaborne oil and a fifth of its liquefied natural gas passed before the war. The third is depth, the ability to absorb strikes on home soil and keep fighting on interior lines.

For Washington, the logic is political rather than existential. The United States enjoys military capabilities that Iran cannot match and a dense network of bases across the Gulf and the wider region, backed by carrier strike groups in adjacent waters. Yet American power here is expeditionary. It is projected thousands of miles from home, sustained by long and exposed logistics chains, and constrained by the patience of Gulf hosts who sit within range of Iranian fire and by an American electorate with little appetite for a protracted war. President Trump, therefore, fights under a clock that Tehran does not face.

Iran is also not isolated. Neither China nor Russia will accept the collapse of the Islamic Republic, and both have an interest in a conflict that ties down American resources. Their support has so far been material and diplomatic rather than military. Iran-approved tankers, many bound for China and India, have continued to move through the Strait under escort, sustaining Iranian revenue and keeping the regime in the fight. That backing has clear limits. Beijing and Moscow will bleed Washington through Tehran’s endurance, but neither intends to confront the United States directly.

Phase One: Pre-War Negotiations

The war was preceded by a genuine diplomatic track. Through late 2025 and into February 2026, indirect talks mediated by Oman addressed uranium enrichment, Iran’s ballistic missile programme and the sequencing of sanctions relief. As late as mid-February 2026, Iranian officials reported an understanding on the guiding principles for resolving the nuclear dispute, and the two sides appeared close to an agreement.

That track ran in parallel with preparation for war. The Congressional Research Service records a sustained American military build-up from late December 2025 through late February 2026, and the Treasury imposed fresh sanctions on Iran’s oil shipping network in the final week of February. The negotiation and the mobilisation advanced together, and when the choice came, force displaced diplomacy. The context was the unresolved legacy of the June 2025 Twelve-Day War, opened by Israel and widened by American strikes on Iranian nuclear sites, whose ceasefire had held only uneasily into the new year.

Phase Two: The Opening Campaign, 28 February 2026

On 28 February 2026, the United States and Israel launched joint strikes, designated Operation Epic Fury by Washington and Operation Roaring Lion by Israel. The campaign targeted nuclear facilities, military infrastructure and the leadership itself. Ali Khamenei was killed in the opening strikes, alongside senior commanders, and the declared purpose extended beyond the nuclear and missile programmes to regime change.

The decapitation did not produce collapse. Iran’s response was regional in scope and sustained over days. Missile and drone salvoes struck Israel and American installations across the Gulf, with attacks reaching the United Arab Emirates, Jordan and Bahrain, and American and Israeli strikes in turn hitting Iran-aligned militias in Iraq. From Lebanon, Hezbollah opened a second front against Israel, drawing Israeli ground operations into southern Lebanon and a parallel Lebanese war that killed thousands and displaced more than a million people before its own separate truce.

The decisive Iranian move was maritime. Tehran closed the Strait of Hormuz to foreign shipping, the Revolutionary Guard asserting control of the waterway and permitting passage only to approved vessels. The immediate consequence was a sharp contraction in traffic through the world’s most important oil chokepoint and the first tremors of the energy and inflation shock that has defined the war’s global footprint.

Phase Three: The Pause and the Islamabad Memorandum

The first sustained opening for de-escalation came through regional mediation, not Western diplomacy. On 8 April 2026, Pakistan brokered a two-week ceasefire between the United States and Iran. Tehran had rejected an earlier Pakistani proposal for a forty-five-day framework and tabled its own ten-point plan, and the truce that emerged traded a suspension of strikes for the reopening of the Strait to commercial traffic. President Trump extended the ceasefire indefinitely later in April, though violations by both sides continued and an American naval blockade of Iranian ports ran in parallel.

The diplomatic peak was the fourteen-point Islamabad Memorandum of Understanding, announced on 14 June and signed by both presidents on 17 June. The document set a sixty-day window for negotiations on the war’s core disputes. Its principal provisions, drawn from the text released after the signing, were as follows:

  • A permanent termination of military operations on all fronts, understood to extend to the Israel-Hezbollah front in Lebanon, though neither Hezbollah nor the Lebanese government was party to the text.
  • Safe passage for commercial vessels through the Strait of Hormuz on a best-efforts basis and without charge for an initial sixty days, with Iranian demining to be completed within thirty days.
  • A commitment by Iran to open a dialogue with Oman and with the other Gulf littoral states on the future administration of the Strait in line with international law.
  • A pathway on the nuclear file centred on the down-blending of near-weapons-grade uranium under supervision by the International Atomic Energy Agency.
  • A phased, conditional easing of sanctions calibrated to Iranian compliance.
  • An American undertaking, with regional partners, to develop a reconstruction and development plan for Iran valued at no less than three hundred billion dollars.

The memorandum was the war’s most significant breakthrough and also its most fragile. It reopened the Strait toll-free and lifted the naval blockade, easing pressure on energy markets, but it deferred every hard question, above all the long-term status of the waterway and the verification of the nuclear commitments, to talks that had barely begun.

Phase Four: The Hormuz Relapse

The renewed war grew directly out of the memorandum’s central ambiguity. On 6 and 7 July, three vessels were attacked in the Strait, Iran treating passage outside its designated corridor as a breach of the terms and the United States treating the attacks as a violation of the guarantee of safe transit. Each side accused the other of breaking the agreement, and the accord came apart within weeks of its signing.

The United States responded with a sustained air campaign. By mid-July, American forces were conducting strikes over consecutive days against Iranian air defences, Revolutionary Guard patrol craft and shipping-related targets, disabling at least one tanker bound for Kharg Island, Iran’s principal oil export terminal. Iran struck back at tankers in and around Omani waters and resumed missile fire at American partners, with Qatar, Bahrain and Jordan all coming under attack or interception in the same days.

Tehran has hardened its position rather than softened it. Iranian officials have described the Strait as an unbreakable red line, warned that no oil or gas will leave the region while American strikes continue, and stated that they have no current plans to negotiate. Washington has been equally ambivalent, with President Trump publicly dismissing the value of the memorandum he had signed and floating a twenty per cent toll on Strait traffic that his own Secretary of State had earlier rejected as unworkable. Only two days of direct talks had taken place under the sixty-day framework before this collapse.

This phase exposes the resource and response limits on both sides. Iran cannot indefinitely sustain a closed Strait without strangling the export revenue on which it depends, and each escalation invites strikes it cannot fully absorb. The United States can degrade Iranian capabilities from the air but cannot compel Iranian consent, and every week of disruption raises the political and economic costs it carries at home and among its Gulf hosts. It is precisely here that Chinese and Russian backing matters, keeping Iran solvent and supplied while stopping short of a direct confrontation that would serve neither power.

The Munitions Problem: American Attrition and Its Strategic Cost

Beneath the phase-by-phase escalation runs a quieter constraint that may prove more decisive than any single exchange of fire. American munitions stocks are being drawn down at a rate that leading analysts and reporting now describe as unsustainable. This is not an Iranian talking point. It rests on an analysis by the Center for Strategic and International Studies, whose findings CNN reported and corroborated through several people familiar with internal Defense Department stockpile assessments.

By the time full-scale fighting paused at the April ceasefire, the United States had expended a substantial share of its most critical precision munitions. The picture, drawn from the CSIS analysis, is set out below.

Source: Center for Strategic and International Studies analysis, reported by CNN (April and July 2026).

Figure 2. Share of key US munitions stockpiles expended by the April 2026 ceasefire.

The arithmetic of replenishment is the heart of the problem. According to the delivery schedules cited by CSIS, the Pentagon is receiving roughly fifteen new Tomahawks and twenty new Patriot missiles a month, with no THAAD interceptors forecast for delivery during 2026 at all. On those rates, restoring inventories to their pre-war levels would take three years or more, and expanding them beyond that would take longer still. Mark Cancian of CSIS, a former Marine Corps colonel and one of the analysis’s authors, has warned that continued fighting at the July tempo would push stocks toward a new and higher level of risk for any contingency in the western Pacific.

Two features make this more than a temporary supply concern. The first is the cost asymmetry, which runs directly against the United States. Iran fields Shahed-type drones costing between twenty and fifty thousand dollars each, while the Patriot interceptors used to defeat them cost in the region of several million dollars apiece. As Senator Mark Kelly has put it, the confrontation has become a mathematics problem, in which cheap and plentiful munitions are traded against scarce and expensive ones. Iran’s capacity to manufacture drones and short and medium-range missiles at scale means it can keep firing long after the defender’s most valuable interceptors are gone. The reported cost of closing the gap reflects this, with the Army seeking well over twenty billion dollars simply to replace THAAD and Patriot expenditures, inside a war supplemental that reporting has placed in the range of eighty to one hundred billion dollars.

The second feature is strategic rather than budgetary. The munitions being consumed against Iran are precisely those the United States would need to deter or fight a near-peer adversary. CSIS concluded that remaining inventories are no longer sufficient to confront a power such as China, and that the campaign has opened what Cancian described as a window of increased vulnerability in the western Pacific. In other words, a war intended to demonstrate American resolve in the Gulf is measurably eroding American deterrent credibility in the theatre Washington itself regards as decisive. If the fighting continues, conventional stocks will not suffice, and the years and extraordinary resources required to rebuild them would leave the United States materially weaker and its global influence diminished for the duration. This is the deeper reason that time favours Tehran, and it should be read directly into the endgame calculations that follow.

Phase Five: The Ground-War Scenario

The most dangerous phase has not yet arrived, and both sides retain reasons to avoid it. A ground campaign would be the lethal turning point of the war, and its logic runs outward rather than inward. Committing forces to Iranian soil or drawing them into a wider land conflict across the region would dissolve the containment that the air and maritime phases have so far preserved.

Such a phase would almost certainly draw in Iran’s regional partners in the open. The militias of Iraq, the remnants of Hezbollah in Lebanon and aligned forces elsewhere would treat a ground war as a general mobilisation, and the fighting would penetrate deep into the wider Middle East rather than remaining a bilateral exchange. The likely consequence would be the sustained interruption of oil production and export across the Gulf, not merely the harassment of transit through a single strait. A prolonged halt on that scale would convert the present disruption into a full global energy crisis, with severe and lasting inflationary effects across importing economies.

The very severity of this scenario is what has, so far, restrained it. For Washington, a land war reverses every asymmetry that favours it, trading standoff advantage for a manpower-intensive campaign at the end of a long supply line and against a population fighting at home. For Tehran, it risks the destruction of the state the regime is fighting to preserve. Deterrence in this phase rests less on capability than on the shared recognition that neither side can control what a ground war would unleash.

Phase Six: The Endgame and The Question of Victory

Every trajectory ultimately returns to the negotiating table, because neither side can impose a decisive outcome the other will accept. The harder question is who emerges able to claim victory.

The asymmetry of stakes shapes the answer. Iran fights on its own territory, where endurance itself is a form of success and where the survival of the regime after a decapitation strike already reads, in Tehran’s narrative, as a strategic win. The United States fights far from home, where the passage of time works against it, where logistics and sustainment remain a structural vulnerability, and where the depletion of precision munitions set out above steadily narrows its options the longer the war runs. A war that neither ends cleanly nor delivers regime change therefore carries a heavy price on two fronts, political at home and strategic abroad, as every week of fighting draws down the very stocks on which American deterrence of China and North Korea depends. A president who opened the campaign promising a swift and total resolution has an incentive to declare success on almost any terms and a corresponding exposure if the war grinds on without one.

This is why serious mediation now matters more than the next exchange of fire. The diplomacy to date has been carried out by regional actors, Pakistan, Qatar and Oman, operating close to the conflict and, at times, close to its firing lines. A durable settlement requires weight that regional mediators alone cannot supply. The European Union, as a party with a direct stake in energy stability and non-proliferation and without a combatant’s exposure, is well placed to underwrite a serious peace process, guarantee the Strait arrangements and anchor the nuclear verification regime. A sincere and sustained effort of that kind, rather than another improvised pause, is the only path out.

The underlying conclusion is straightforward. This war serves no one’s interests. It has killed thousands, destabilised the Gulf, imposed an energy and inflation shock on the global economy, and left both principals worse placed than the pre-war negotiations from which they walked away. The Islamabad Memorandum showed that the shape of a settlement is already visible. What is missing is not a plan but the political will, on both sides and among those able to guarantee it, to hold to one.

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Tahir Azad

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