Obama’s new nominee for Secretary of Defense, Ashton Carter, has a particularly important skill set for modern times: he’s an expert on nuclear weapons. That will make him a useful leader to have at the helm when it comes to negotiations with Iran, as well as when dealing with smaller nuclear nuisances like North Korea. But the challenges of nuclear power don’t end with these irrational actors; in the future, more countries around the world will find themselves considering nuclear as a source of base-load power, especially because (as we often say) it is a far greener energy source than fossil fuels.What is the world to do with a power source that is on the one hand so promising and on the other so dangerous? Many states eyeing an investment in nuclear aren’t strong enough to ensure that the materials don’t fall into the wrong hands (and in certain cases, those wrong hands are pretty close to the levers of power). This is no short-term dilemma, either; highly-enriched uranium or plutonium stays potent for thousands of years.Soon-to-be Secretary Ashton Carter supplied an answer to this problem in our magazine’s pages way back in 2006, with co-author Stephen LaMontagne. They suggest that the solution is a multi-national regime that can “provide enrichment and spent fuel removal services to states that abstain from domestic enrichment and reprocessing, submit to strict safeguards (such as those stipulated in the IAEA Additional Protocol), and reaffirm their intention not to pursue nuclear weapons.” As the authors point out, less-developed countries have strong incentives to work with a multi-national body instead of going it alone (for one thing, it’s less expensive), and under this arrangement, everybody’s happy: many countries that need it get a reliable source of power, and the world at large doesn’t face a nuclear free-for-all.You can read the argument in full here. Agree or disagree, if there’s one person who knows his light water from his heavy, it’s Ashton Carter. With Iran our biggest current threat (as our editor Adam Garfinkle says), we’re glad President Obama will have Carter’s expertise close at hand.