Nuclear Weapons Plant Security: There are ongoing concerns about terrorist groups acquiring nuclear bomb-making material. The notion of terrorist organizations using nuclear weapons (especially very small ones, such as suitcase nukes) has been a threat in American rhetoric and culture. Various acts of civil disobedience since 1980 by the peace group Plowshares have shown how nuclear weapons facilities can be penetrated, and the groups actions represent extraordinary breaches of security at nuclear weapons plants in the United States. On July 28, 2012, three members of Plowshares cut through fences at the Y-12 National Security Complex in Oak Ridge, Tennessee, which manufactures US nuclear weapons and stockpiles highly enriched uranium. The group spray-painted protest messages, hung banners, and splashed blood. The National Nuclear Security Administration has acknowledged the seriousness of the 2012 Plowshares action, which involved the protesters walking into a high-security zone of the plant, calling the security breach "unprecedented". Independent security contractor, WSI, has since had a weeklong "security stand-down," a halt to weapons production, and mandatory refresher training for all security staff. Non-proliferation policy experts are concerned about the relative ease with which these unarmed, unsophisticated protesters could cut through a fence and walk into the center of the facility. This is further evidence that nuclear securitythe securing of highly enriched uranium and plutoniumshould be a top priority to prevent terrorist groups from acquiring nuclear bomb-making material. These experts have questioned "the use of private contractors to provide security at facilities that manufacture and store the government's most dangerous military material"