The watcher in the water

"TRUST, but verify." That was Ronald Reagan's mantra for nuclear agreements, though the proverb itself is Russian. But verifying that a country is not cheating on one important matter of nuclear diplomacy, the manufacture of plutonium, is hard. At the moment, it can be done only by visiting the site of any and every nuclear reactor which could be employed for the task--even then, one might be hidden away. But if a project now being undertaken in America works well, hiding reactors will become mu...