"The specter of nuclear warfare waged by North Korea or Iran has hung over the world in recent months. But beyond that fear and foreboding looms a more far-reaching threat: the vast amount of nuclear bomb-grade material scattered across the globe. And it wasn't Kim Jong Il or the ayatollahs of Iran who put it there. America did." Those are the opening lines of a new expose by the Chicago Tribune reporter Sam Roe. [includes rush transcript]

Roe's investigation has found several tons of US nuclear bomb-grade material distributed under the Cold War Atoms for Peace program remains scattered across the planet. The US government has failed to retrieve forty tons of highly enriched uranium -- enough to make over 1,400 nuclear weapons. While the Bush administration says its trying to remove weapons-grade fuel from several research reactors around the world, many nuclear experts believe the US does not know how much enriched uranium exists abroad -- or even where it exists.

• Sam Roe, staff reporter at the Chicago Tribune. His series on the U.S. Cold War program "Atoms for Peace" is featured this week.