7 Tense Moments in US-Iran Relations

The United States and Iran were close allies until the 1979 Iranian Revolution that deposed the U.S.-backed shah and transformed Iran into a theocracy. The hardline Iranian regime cast the United States as “The Great Satan,” and the two nations became bitter adversaries, with President George W. Bush famously including Iran in his “axis of evil” speech in 2002.

The U.S. and Iran have never officially been at war, but they have engaged in decades of high-stakes brinkmanship. Iran has funded militant groups that have targeted the U.S. and its allies in the Middle East, while the U.S. has carried out assassinations and military strikes against Iranian targets. And as Iran has pursued a nuclear program widely believed by Western powers to have weapons ambitions, the U.S. and allies have imposed severe sanctions to try to stop it.

Here are seven critical moments in the history of U.S.-Iran relations when tensions ran the highest.

Iran has always been an oil-rich nation, and the British had a monopoly on Iranian oil until 1951. That’s when an Iranian lawmaker named Mohammad Mossadegh became prime minister and nationalized Iranian oil production.

“The British were unhappy with this situation and wanted to overthrow Mosaddegh, but they didn't have the ability to do it themselves,” says Kelly Shannon, a visiting scholar with the Institute for Middle East Studies at George Washington University. “So the British convinced the Eisenhower administration and the CIA to plan a coup and execute it.”

The first coup attempt was botched and the shah fled Iran in the face of angry protests. A second coup attempt, however, succeeded and the shah was restored to power, replacing the democratically elected Mossadegh. In 1954, the shah agreed to a lucrative deal that gave U.S., British and French oil companies 40 percent ownership of the Iranian oil industry for 25 years. Dwight D. Eisenhower rewarded the shah’s loyalty with the “Atoms for Peace” initiative, in which the U.S. gave Iran technology and enriched uranium for launching a nuclear energy program.

For the U.S., the shah of Iran became a critical Cold War ally.

“Having a reliably anti-communist country on the border with the Soviet Union would help keep the Soviets out of the Middle East,” says Shannon, “and would help keep Middle Eastern oil out of Soviet hands and flowing to the West.”

The shah was popular at first among Iranians, but over the next two decades he became increasingly authoritarian. Iranians who opposed the shah’s ambitious modernization program or criticized economic inequality were rounded up and tortured by the SAVAK, the government's notorious secret police.

While the shah’s political enemies saw him as a dictator, Islamic hardliners like Ayatollah Khomeini were outraged when Iranian women were given the right to vote and allowed to appear in public without the hijab. Both of these groups came to resent the U.S. as the “puppet master” pulling the shah’s strings in Iran, says Shannon.

In 1979, massive protests erupted in Iran and the shah fled the country, eventually landing in the United States for cancer treatment. Ayatollah Khomeini returned from exile and helped found the Islamic Republic of Iran, a theocratic regime that rejected the shah’s program of Westernization and secularism. To Ayatollah and his supporters, the U.S. became “The Great Satan.”

On November 4, 1979, a group of Iranian college students stormed the U.S. embassy in Tehran and took 52 Americans hostage. The students demanded the extradition of the shah to stand trial in Iran, but the Carter administration responded by severing diplomatic ties with Iran and imposing harsh sanctions on Iranian oil exports.

The hostage crisis lasted a torturous 444 days. Politically, it destroyed President Jimmy Carter’s chance of reelection in 1980, but it proved useful for Ayatollah and his anti-American, anti-Western rhetoric.

“The Ayatollah Khomeini used the hostage crisis at the U.S. embassy—what he called the ‘den of spies’—to outmaneuver his political opponents and consolidate power in the hands on the religious hardliners,” says Shannon.

U.S.-Iranian relations worsened dramatically in the 1980s. In 1983, two trucks loaded with explosives killed 241 U.S. service members at a military base in Beirut, Lebanon. The U.S. blamed Hezbollah, a Lebanese militant organization backed by Iran. President Ronald Reagan labeled Iran a “state sponsor of terror,” a designation that imposed strict military sanctions, including restrictions on the sale of military equipment and dual-use technology.

Secretly, however, the Reagan administration flouted its own sanctions by selling arms to Iran in exchange for the release of American hostages held by Hezbollah. The proceeds from those weapons sales were then used to fund anti-communist Contra rebels in Nicaragua, an illegal scheme later exposed as the Iran-Contra affair.

Tensions ratcheted up again in 1988 when a U.S. Navy vessel struck an Iranian mine in the Persian Gulf, injuring 10 sailors. This was during the Iran-Iraq War, when both countries were targeting each other’s oil tankers. The USS Samuel B. Roberts was escorting a neutral Kuwaiti tanker when it struck the Iranian mine. In retaliation, the U.S. launched Operation Praying Mantis, which sank or severely damaged much of Iran’s operating forces in the Persian Gulf.

Tragically, in July 1988, U.S. forces mistakenly fired a guided missile at Iran Air Flight 655, a passenger plane flying from Tehran to Dubai. All 290 people on board were killed.

“For the Iranian regime and its supporters, the downing of Flight 655 was a big moment,” says Shannon. “They could say, ‘See, the Americans are evil. They're shooting our civilians out of the sky.’ At the same time, Iran was very much supporting proxy groups in the Middle East and harassing American allies, so it went both ways.”

During the 1990s, the U.S. ramped up sanctions against Iran in hopes of weakening the regime and slowing its acquisition of weapons and nuclear technology. In 1995, the Clinton administration imposed a complete oil and trade embargo on Iran.

Then came the terrorist attacks of September 11, 2001, when nearly 3,000 Americans were killed by al-Qaida operatives. In a surprising move, the Iranian regime—itself a sworn enemy of al-Qaida and the Taliban—secretly offered to help the U.S. root out the perpetrators of 9/11.

Instead, the U.S. grouped Iran with other state sponsors of terror. In his 2002 State of the Union address, President George W. Bush described Iran, Iraq and North Korea as an “axis of evil” and accused the Iranian regime of aggressively pursuing weapons of mass destruction and repressing its people.

“The Iranians felt very betrayed,” says Shannon. “They thought they had offered an olive branch of sorts and then Bush named them one of the three most evil states in the world."

Months after Bush’s “axis of evil” speech, it was revealed that Iran was actively pursuing a nuclear program that Western governments said had weapons ambitions, despite international sanctions and trade embargoes. The U.N. Security Council ordered Iran to halt uranium enrichment, but the regime continued to operate nuclear facilities.

In 2015, after a decade of negotiations, the U.S. joined the European Union, China and Russia in signing the Joint Comprehensive Plan of Action, or JCPOA, a deal with Iran to scale back punitive economic sanctions in return for curbing its nuclear program. The Obama administration hailed the JCPOA as the beginning of a new era for Iran and its people, while critics feared that the deal would only empower the Iranian regime to increase its support of militant organizations.

In 2018, President Donald Trump withdrew the U.S. from the JCPOA and hit Iran with another round of damaging sanctions. Iran responded by resuming and expanding its uranium enrichment program in defiance of the United Nations and the terms of the deal.

The collapse of the JCPOA inflamed tensions between the U.S. and Iran. In 2019, there was a spate of tanker attacks in the Persian Gulf that the U.S. blamed on Iran. When the Trump administration deployed additional U.S. troops to the region, protests erupted. Iran-backed militias tried to breach the U.S. Embassy compound in Baghdad, chanting “death to America.”

On January 3, 2020, Trump ordered a drone strike that killed General Qassem Soleimani, the most powerful military commander in Iran. This was the first time the U.S. had assassinated an Iranian leader, signaling a major military escalation between the two nations.

“This was not something the U.S. had done before and it was very much public—it wasn’t covert,” says Shannon. “This enraged the regime.”

Soon after Soleimani’s killing, Iran accidentally shot down a Ukrainian passenger plane leaving Tehran for Kyiv. The aircraft was struck by two surface-to-air missiles fired by the Islamic Revolutionary Guard Corps after takeoff on January 8, 2020, amid heightened military tensions following Iran’s missile strikes on U.S. forces in Iraq. All 176 people aboard were killed.

On October 7, 2023, the militant Palestinian group Hamas launched a devastating attack on Israel, killing about 1,200 people, most of them civilians, and taking hundreds more hostage. Iran had provided Hamas with funding, weapons and training for decades.

When Israel executed several high-profile Hamas and Hezbollah leaders, Iran launched its first direct attack on Israel in the form of a massive missile and drone strike in 2024. Israel retaliated with strikes on Iranian military sites.

In June 2025, the Trump administration ordered an air strike on Iran’s nuclear facilities, marking the first time in decades that U.S. forces had struck inside Iranian territory outside of proxy battles, says Shannon. Using B-2 bombers and bunker-buster bombs, the U.S. hit key nuclear sites in an operation dubbed Operation Midnight Hammer, aimed at degrading Iran’s nuclear enrichment infrastructure.

Shannon says that it’s important to distinguish between the Iranian regime and the Iranian people. Not only is the Iranian regime a state sponsor of terror, but it also represses its own people, who have taken to the streets demanding basic human rights and democracy.

“The Iranian people have suffered the most horrific oppression for the last 47 years,” says Shannon. “I see them as being on the front line of the global battle between democracy and autocracy.”