A nuclear reactor was sold to Iran as part of President Eisenhower's "Atoms for Peace" program. But even then the US had concerns about what might happen if the Shah fell to 'domestic dissidents.'
In 1967, under the "Atoms for Peace" program launched by President Eisenhower, the US sold the Shah of Iran's government a 5-megawatt, light-water type research reactor. This small dome-shaped structure, located in the Tehran suburbs, was the foundation of Iran's nuclear program. It remains at the center of the controversy over Iranian intentions, even today.
That is because Iran says it needs more fuel for the reactor, which it insists it uses for basic research, and to produce medical isotopes. And the Tehran Research Reactor runs on uranium that is some 20 percent U-235 – an enrichment level higher than that currently produced by Iran's Natanz enrichment facility.
Now Iran has agreed in principle to send most of its current stockpile of low-enriched uranium abroad, so that some other country – most likely Russia – can produce this more-highly enriched fuel for them. In any case, that is what US and European officials say occurred at this week's meeting between Iran and six western powers.