WASHINGTON — When President Donald Trump ordered a military strike on Iran’s nuclear program, he was confronting a crisis that the United States unwittingly set in motion decades ago by providing Iran with the seeds of nuclear technology.

Tucked into the northern suburbs of Tehran, the Iranian capital, is a small nuclear reactor used for peaceful scientific purposes, which has so far not been a target of Israel’s campaign to eliminate Iran’s nuclear weapons capability.

The Tehran Research Reactor’s real significance is symbolic: It was shipped to Iran by the United States in the 1960s, part of President Dwight D. Eisenhower’s “Atoms for Peace” program that shared nuclear technology with U.S. allies eager to modernize their economies and move closer to Washington in a world divided by the Cold War.

Today, the reactor does not contribute to Iran’s enrichment of uranium, the arduous process that purifies the raw ingredient of nuclear bombs into a state that can sustain a massive chain reaction. It runs on nuclear fuel far too weak to power a bomb. Several other nations, including Pakistan, bear at least as much responsibility for Iran’s march to the threshold of nuclear weapons capability, experts say.

But the Tehran reactor is also a monument to the way the U.S. introduced Iran — then governed by a secular, pro-Western monarch — to nuclear technology.

Iran Nuclear Program Became Object of National Pride

Iran’s nuclear program quickly became an object of national pride, first as an engine of economic growth and later, to the West’s dismay, as a potential source of ultimate military power.

It is a legacy of a dramatically different world, one in which the U.S. had yet to grasp how fast the nuclear secrets it unlocked at the end of World War II would pose a threat to the United States.

“We gave Iran its starter kit,” said Robert Einhorn, a former arms control official who worked on U.S. negotiations with Iran to limit its nuclear program.

“We weren’t terribly concerned about nuclear proliferation in those days, so we were pretty promiscuous about transferring nuclear technology,” said Einhorn, now a senior fellow at the Brookings Institution. “We got other countries started in the nuclear business.”

The Iran that received an American research reactor in 1967 was very different from the country ruled today by clerics and generals. It was led then by a monarch, or shah, Mohammad Reza Pahlavi, a Swiss-educated aristocrat installed in a 1953 coup backed by the CIA, to the lasting anger of many Iranians.

Pahlavi was determined to modernize his nation and make it a world power, with U.S. backing. He liberalized Iranian society, promoting secularism and Western education even as he harshly repressed political opposition. He banned the woman’s veil and promoted modern art — Andy Warhol once painted his portrait — while investing in literacy and infrastructure.

Kick-started by “Atoms for Peace,” Pahlavi budgeted billions of dollars for an Iranian nuclear program that he saw as a guarantee of his country’s energy independence, despite its existing vast oil production, and a source of national pride. The United States welcomed young Iranian scientists to special nuclear training courses at the Massachusetts Institute of Technology.

Iran Strikes Deal With European Allies

Expanding its program in the 1970s, Iran struck deals with its European allies. During a visit to Paris in 1974, Pahlavi was celebrated at Versailles before signing a billion-dollar agreement to purchase five 1,000-megawatt nuclear reactors from France.

At first, the shah was a poster boy for the peaceful use of nuclear power. A group of New England utility companies put out full-page ads featuring an image of the shah, who was then widely admired in the United States. Pahlavi “wouldn’t build the plants now if he doubted their safety,” the ad said. “He’d wait. As many Americans want to do.”

But although the United States had persuaded Iran to sign the 1968 Nuclear Nonproliferation Treaty, in which the country accepted international safeguards and officials forswore nuclear weapons, suspicions about Pahlavi’s intentions were growing in Washington. A New York Times article in 1974 noted that Iran’s reactor deal with France made “no public mention of safeguards against using the reactors as a base for making nuclear weapons.”

Soon the shah was talking about Iran’s “right” to produce nuclear fuel at home, a capability that can also be applied to nuclear weapons development. He denounced discussions about outside limits on Iran’s nuclear activity as a violation of national sovereignty — talking points still used by Iran’s leadership. As Washington expressed greater concern, Pahlavi turned to a wider range of nations for nuclear assistance: Germany would build more reactors, and South Africa would supply raw uranium, or “yellowcake.”

By 1978, the Carter administration was alarmed enough to insist that an Iranian contract to purchase eight American reactors be amended. The new version would prohibit Iran from reprocessing without permission any U.S.-supplied fuel for its nuclear reactors into a form that could be used for nuclear weapons.

American Reactors Weren’t Delivered

The American reactors were never delivered. In 1979, the Islamic Revolution, fueled in part by hatred of the U.S. and its support for the shah, swept across Iran and deposed Pahlavi.

For a time, the problem of Iran’s nuclear ambitions seemed to have solved itself. Iran’s new clerical rulers, led by Ayatollah Ruhollah Khomeini, initially showed little interest in continuing an expensive project associated with the shah and Western powers.

But after a brutal eight-year war with Iraq in the 1980s, Khomeini reconsidered the value of nuclear technology. This time, Iran turned east — to Pakistan, another “Atoms for Peace” beneficiary that was by then within a decade of testing a nuclear bomb. The Pakistani scientist and nuclear black marketeer Abdul Qadeer Khan sold Iran centrifuges to enrich uranium to bomb-grade levels of purity.

Iran’s acquisition of centrifuges was the real reason its nuclear program escalated into a global crisis, said Gary Samore, the top White House nuclear official in the Clinton and Obama administrations.

“Iran’s enrichment program is not the result of U.S. assistance,” Samore said. “The Iranians got their centrifuge technology from Pakistan, and they have developed their centrifuges based on that Pakistani technology — which itself was based on European designs.”

But those centrifuges were put to use by an Iranian nuclear establishment created by the U.S. decades earlier.

For years, Iran secretly advanced its nuclear program, building more centrifuges and enriching uranium that could one day be fashioned into a bomb. After Iran’s secret nuclear facilities were exposed in 2002, the U.S. and its European allies demanded that the country stop its enrichment and come clean about its nuclear activities.

After more than 20 years of diplomacy — and now airstrikes by Israel and the United States — the confrontation remains unresolved. Despite Trump’s initial claims that Saturday’s bombing raid “totally obliterated” three Iranian nuclear sites, portions remain intact.

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This article originally appeared in The New York Times.

By Michael Crowley
c. 2025 The New York Times Company