The security cordon around the US could be tightened with an improved system for catching people trying to smuggle nuclear material. The detectors can ferret out fissile material such as uranium, even if it is sealed in a lead container, and could be installed within the year. The amount of nuclear material recorded as missing from licensed sites around the world suggests smuggling is rife, but inadequate equipment at national borders means seizures by customs are few and far between. US borders are patrolled by officers wearing "pagers" that detect the high levels of gamma radiation emitted by nuclear material....