We can bomb, invade or assassinate Iran 's leaders to stop their nuclear weapons development, but these actions are extreme, almost unthinkable. They will seem reasonable in hindsight if New York , London , or Tel Aviv suffers from an Iranian nuclear attack, but by then it will be too late.

That leaves us with trade sanctions as the primary tool for influencing Iran . Unfortunately trade sanctions are feeble. The only real effect of past sanctions has been to deny parts and maintenance to Iran 's civilian aircraft fleet, which has made it very unsafe. Large Iranian civilian aircraft are sometimes flown without functioning avionics, which means that pilots rely upon what they see out the window for much of their navigation.

There is, however, one sanction against the Iranian nuclear threat that will work, is relatively easy to implement, and should have few unintended consequences. This sanction is to deny American educational and professional opportunities to Iranian government-sponsored nuclear scientists and engineers and their families, and to deny American educational opportunities to the extended families of Iranian dictators.

Tyrants love their families, too, and they want the best for their children. The most consistent gift that tyrants, kleptocrats, and the ruling families of dysfunctional countries bestow upon their extended families is an education at an American university. Two dozen members of the bin Laden family were studying at American universities at the time of the 9/11 attack; the Saudi government chartered an airplane to evacuate them. American university education is admired and sought by people worldwide. Just as influential Washington Democrats who created the public school mess make sure to avoid DC public schools for their own children, tyrants know that a university education in their own educational systems means consigning their children to ignorance. Education in rogue states stifles creativity with its master/apprentice relationships between professors and students, and features a lot of head pounding, rote memorization. The creativity and problem solving skills taught at American universities, and mastery of the English language, are vital for scholars today. American education is also a status symbol. Dictators are driven to achieve power and status, and to think that their families will be denied this most potent of symbols of power and status will positively modify their behavior.

Iranian government-sponsored nuclear scientists and engineers should also be denied study at American universities. These scientists and engineers place immense value on travel and contact with American scientists and engineers and study at American universities. During my career as a CIA officer, I never met a rogue state weapons scientist who considered himself evil. They actually think they're just practicing and advancing their field of study. To brand these people as the potential mass murderers that they are and to halt the publication of their papers and their study at American institutions would severely limit their research and professional advancement. They'd know that to contribute to development of Iranian nuclear weapons would end their careers as respected scientists and engineers.

For decades we have had Iranians at American universities, sponsored by the Iranian government, studying the engineering and sciences necessary to create nuclear weapons. Before leaving for my overseas tours as a CIA officer, I had an on-the-job training assignment at a CIA office in the United States . One of my assignments was to meet foreign government-sponsored nuclear engineers and nuclear scientists at American universities and develop them for recruitment. I've seen them; I've met them.

There are consequences of this sanction, but they are minor. Academics at universities will be concerned that these moves threaten academic freedom. A friend of mine actively volunteers his time recruiting the children of dominant families in the Middle East on behalf of his Ivy League university. He's a well-meaning man who believes that these young men and women will return to their native lands bearing the light of knowledge and reason, which will encourage their societies to become more open and free. These are valid concerns, but the nuclear threat is serious and immediate and the number of people restricted would be very small.

If we prevent Iranian government-sponsored nuclear scientists and engineers and the extended families of Iranian rulers from traveling to and studying in America , and we enlist the support of our allies to enact the same sanction in Europe , these actions may well lead to the end of the Iranian nuclear threat.

Ishmael Jones is a former officer in the CIA's clandestine service, and author of "The Human Factor: Inside the CIA's Dysfunctional Intelligence Culture."