Why is Pretoria so jealously guarding it fissile material?

In the early hours of 28 July 2012, three people, one of them an 82-year-old nun named Megan Rice, broke into the Y-12 Nuclear Security Complex near the city of Oak Ridge, Tennessee. Y-12 is where all of America’s highly enriched uranium (HEU) – for making nuclear weapons – is made or stored: about 400 000 kg of it, according to The New Yorker magazine.

Rice and two others from the Plowshare anti-nuclear activist group managed to cut through three fences, paint slogans and splash blood on the football-field-sized building housing the Y-12 arsenal before a few of the 500-odd security guards finally arrived to arrest them. This demonstration by Plowshare – one of many over the last 35 years – was designed in part to show that America’s nuclear weapons were not secure from theft by terrorists. Which it did.