Babcock & Wilcox nevertheless proceeded to build the facility above ground, the big white castle, with its four turrets and walls. Originally estimated to cost taxpayers about $253 million, the Highly Enriched Uranium Materials Facility wound up costing more than twice that amount. And because it’s not underground, it needs more officers to guard its perimeter. The most secure nuclear-weapons-storage site in the United States, according to the military and civilian experts whom I consulted, is the Kirtland Underground Munitions Storage Complex at Kirtland Air Force Base, in Albuquerque, New Mexico. In satellite photographs, aside from an entrance ramp and an exit ramp, the structure is practically invisible.

After the break-in at Y-12, Wackenhut also lost the contract to provide security at the neighbouring Oak Ridge National Laboratory. But today Wackenhut is still the security contractor at the Savannah River Site, outside Aiken, South Carolina – where about 20,000 pounds of plutonium are stored. Savannah River is a difficult site to protect. It extends across 200,000 acres, and a state highway cuts through the middle of it. In late 2012, Wackenhut received a bonus for its ‘exceptional level of performance’ at the site. The following January, Wackenhut failed a Department of Energy security test at Savannah River, allowing commandos to seize fissile materials in a mock attack. A representative of Wackenhut – now owned by a private equity firm and renamed the Centerra Group – later emphasized that the overall security audit had a ‘satisfactory outcome’.

A company called National Strategic Protective Services (NSPS) won the $182 million contract to replace Wackenhut at the Oak Ridge laboratory, where some weapons-grade uranium is kept. NSPS is a joint venture formed by two large security companies. One of them, Triple Canopy, has for years provided security at American embassies and bases in Iraq. The Department of Justice alleged in 2012 that ‘Triple Canopy knowingly billed the United States for hundreds of foreign nationals it hired as security guards who could not meet firearms proficiency tests established by the army and required under the contract’. The company had recruited guards in Uganda and brought them to Iraq. Many of the guards did not know how to fire their assault rifles accurately or safely – a skill necessary for protecting Al Asad Air Base, a crucial American base during the Iraq war. The Justice Department also claimed that Triple Canopy’s managers in Iraq repeatedly falsified test scorecards to cover up the guards’ lack of proficiency – and that high-level executives at the company were aware of the fraud. ‘For a government contractor to knowingly provide deficient security services, as is alleged in this case, is unthinkable, especially in war time,’ said a Justice Department official. The case is still pending in court.

Triple Canopy was bought last year by the Constellis Group, a conglomerate that has taken over a number of large security firms. One of them, Academi, used to do business under a different name: Blackwater.