A former CIA officer convicted of leaking classified details of an operation to derail Iran's nuclear ambitions would spend 20 years in prison if a judge follows federal sentencing guidelines.

Jeffrey Sterling of O'Fallon, Missouri, will be sentenced next month in Alexandria after his conviction in January. A jury found him guilty of illegally disclosing to journalist James Risen a secret mission to stall Iran's nuclear-weapons program by feeding them deliberately flawed blueprints.

Prosecutors on Monday filed papers urging a severe sentence. They said probation officers correctly calculated a sentencing guidelines range of 20 to 24 years.

But the judge is free to reject the guideline recommendation. Sterling has drawn support from Nobel Peace Prize laureate Desmond Tutu and others who argue Sterling has been treated unfairly.