US vs Iran: Allies to Enemies

In 1951, Iran nationalised its oil industry. Prime Minister Mohammad Mosaddegh argued that Iran should control a resource that had been run under a British-dominated arrangement. That June, he wrote to President Harry Truman, presenting nationalisation as the carrying out of laws passed by Iran's parliament and asking for American support.⁷

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The dispute was about money, but also about power. Who would run the industry? Who would receive its revenues? How much influence could a foreign company keep over a country's affairs? American records of the time acknowledged how strongly Iranians supported nationalisation, and the belief that the old arrangement had given Britain too much influence.¹

Washington and London also saw Iran through the lens of the Cold War. A US National Security Council document of January 1954 stressed Iran's strategic position and the danger it saw of Soviet influence. That was Washington's reading of the situation. It was not evidence that Mosaddegh himself was carrying out a Soviet programme.¹

In August 1953, a coup backed by the CIA and Britain's MI6 overthrew him.²

Declassified records document American planning and participation. Iranians took part too: foreign intervention did not mean that everything inside Iran was directed from abroad. What the record establishes is a covert operation inside an Iranian political struggle.²

The coup strengthened the Shah's hold on power. It also handed his opponents a documented example of outside powers deciding Iran's political future, one they would cite for decades.²

After 1953, Washington sought a stable, friendly Iran and an end to the oil dispute. The 1954 policy record describes both financial support and strategic aims. America's partnership with the Shah was a policy choice, rooted in its view of regional security. It was not an agreement between the United States and every part of Iranian society.¹

In 1979, the monarchy fell. Ayatollah Ruhollah Khomeini became the central figure of a new Islamic Republic. For Washington, a close partner had collapsed. For the revolutionary leadership, America's long support for the Shah shaped how every American move would be read.³

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This was more than a change of government. A state that had been an American partner was being rebuilt around a different political and religious authority, one whose legitimacy rested on overthrowing the order the United States had backed.³

On 4 November 1979, Iranian students stormed the US embassy in Tehran and took Americans hostage. For those who remained captive, the crisis lasted 444 days. To put that into context: the crisis began a year before Jimmy Carter faced re-election, and it ended on the day he left office.⁴

The Carter administration tried several routes to free them. In April 1980, a military rescue mission failed. Secretary of State Cyrus Vance, who had opposed it, resigned. The episode captured the pressures on American leaders: the pull of negotiation, the public demand for action, and the risks of using force.⁴

The International Court of Justice ruled on the seizure in 1980. It separated the initial actions of the militants from the later conduct of Iran's authorities, and found Iran in breach of its international obligations. The case concerned a state's duty to protect diplomats and embassies. It was not a ruling that Iran's grievances about earlier American conduct were unfounded.⁸

The last hostages were released on 20 January 1981, under the Algiers arrangements. Those arrangements also created the Iran–United States Claims Tribunal to settle specified financial claims. Normal diplomatic relations never returned, but the tribunal endured: a working legal channel between two governments that did not otherwise speak.⁹⁴

In September 1980, Iraq invaded Iran. The war lasted until 1988. To put that into context, the Islamic Republic spent eight of its first ten years fighting for survival. The war also brought fighting into the Gulf, and made the security of shipping part of the wider confrontation.⁵

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In July 1987, the UN Security Council adopted Resolution 598, calling for a ceasefire, a withdrawal to recognised borders and further negotiations. The guns did not fall silent that day. The ceasefire took effect more than a year later, on 20 August 1988, and UN observers deployed to supervise it.¹⁰⁵

Even then, the end of the fighting left questions still to negotiate: prisoners, borders, and responsibility for the war.¹⁰

Public hostility did not rule out secret dealings. In the Iran–Contra affair of the 1980s, American officials became involved in selling arms to Iran, partly in connection with Americans held hostage in Lebanon. The official investigation also described proceeds being diverted to Nicaragua's Contra rebels.¹¹

It was no return to the old alliance. It ran through secret channels and became a major scandal in the United States. But it showed that the two governments could oppose each other in public and still explore narrow, sometimes contradictory, arrangements in private.¹¹

The confrontation turned direct again in January 2020. A US strike in Baghdad killed Qassem Soleimani, the commander of the Revolutionary Guards' Quds Force. The Pentagon said it acted to protect Americans and deter future attacks. That was the American justification; it did not independently establish every intelligence claim behind the strike.¹²

These regional clashes were a separate front from the nuclear dispute. Armed groups, military deployments, shipping and direct strikes could shake the relationship even while negotiators were discussing nuclear limits. An agreement on one did not remove the others.¹²⁶

The nuclear dispute was a different kind of argument: what activities were taking place, whether they had been declared, and whether international inspectors could confirm that nuclear material stayed in peaceful use. In June 2003, the International Atomic Energy Agency reported that Iran had failed to meet its obligations to declare nuclear material and related activities.¹³

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A safeguards finding has a precise meaning. Undeclared material or incomplete cooperation can stop inspectors reaching the conclusions they need. It does not, on its own, show that a weapon has been built. The agency's job is to examine the evidence within its mandate.¹³

In December 2015, the agency delivered its assessment of the outstanding questions. Before the end of 2003, it found, Iran had carried out a coordinated effort involving activities relevant to a nuclear explosive device, with some activity later. The work had not gone beyond feasibility and scientific studies and the acquisition of certain technical capabilities.¹⁴

The same report found no credible indications of such activities after 2009. It was a dated judgment of the evidence available in 2015. It did not erase the findings about earlier work, and it could not guarantee the future.¹⁴

That is why negotiators concentrated on things that could be measured and checked, rather than on promises: the scale of enrichment, stocks of nuclear material, the facilities, and the access inspectors needed. Declarations of peaceful intent could not stand in for a mechanism to see what was actually happening.⁶¹⁵

Capability and intention are not the same thing. Equipment and knowledge can have more than one use. Judging a programme means looking at its activities, its material and its evidence, and saying exactly when the judgment was made.¹⁴¹³

On 14 July 2015, Iran reached an agreement with China, France, Germany, Russia, the United Kingdom and the United States, with the European Union coordinating: the Joint Comprehensive Plan of Action. The UN Security Council endorsed it in Resolution 2231. Its core bargain was simple to state: limits on Iran's nuclear programme, checked by inspectors, in exchange for relief from specified sanctions.⁶

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On 16 January 2016, the IAEA confirmed that Iran had taken the required first steps. The EU and the United States then lifted the sanctions the agreement specified. That was relief from particular nuclear-related measures, not the end of every sanction on Iran.¹⁵

The agreement did not ask the two governments to become friends. It let them make a narrow exchange while their other disputes carried on. Supporters said that narrowness was what made real limits achievable. Critics said that limits of different lengths, and no wider regional settlement, left serious dangers untouched.¹⁵¹⁶

On 8 May 2018, President Donald Trump announced that the United States would withdraw and restore its nuclear sanctions. He criticised the agreement's duration and scope, including its silence on missiles and regional activity. Those were his administration's reasons for leaving, not a finding by inspectors that Iran had failed to implement the deal.¹⁶

The withdrawal broke the bargain's logic. Nuclear limits had been exchanged for economic relief, and the exchange depended on the parties providing that relief staying in. Once the United States withdrew its side, the deal no longer balanced. The European statement of 2016 and the American announcement of 2018 describe different moments; neither alone answers whether the diplomacy worked.¹⁵¹⁶

In June 2025, Israeli and US attacks struck Iranian nuclear facilities. On 23 June, the IAEA's Director General, Rafael Grossi, described damage to several sites and warned of the dangers of attacking nuclear installations. He was careful to separate what the agency could establish from what it could not yet assess, particularly underground.¹⁷

Damage to a building, the fate of nuclear material and the survival of expertise are three different questions. A dated technical statement can settle some facts. It cannot, by itself, support a claim that a programme has been destroyed for good.¹⁷

Between Iran and Oman lies the Strait of Hormuz, the passage from the Persian Gulf to the Gulf of Oman and the Arabian Sea. Its importance is the sheer volume of energy that passes through a route with few alternatives. In 2024, according to the US Energy Information Administration, oil flows through the strait averaged about 20 million barrels a day. To put that into context, that was roughly a fifth of all the oil the world consumed.¹⁸

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That figure is a benchmark from before the later conflict, not a live measure of traffic. It explains why any threat to shipping there reaches far beyond Iran and its adversaries, to exporters, buyers, shipping companies and insurers around the world.¹⁸

Some oil can bypass the strait by pipeline, but not all of it. The EIA distinguishes the capacity of those routes from the ability to replace every shipment; the effect of a disruption depends on the product, the spare capacity, and how long it lasts.¹⁹

A strait does not have to be closed to be disrupted. Ships can still pass while delays, costs and uncertainty rise. The EIA counts supply delays and higher transport costs among the consequences of a chokepoint under pressure. Any claim about Hormuz needs evidence about what is actually getting through, as well as statements about intent.¹⁹