In this report, clandestine nuclear attack means a nuclear or radiological attack
• By anyone for any purpose,
• Against the United States and/or U.S. military operations,
• Delivered by means other than (military) missiles or aircraft
A large subset of this threat is the smuggling of nuclear weapons, devices, or materials for use against the United States.
Since the 1950s, there has been sporadic concern about the threat of clandestine nuclear attack (previously referred to by other terms), but little has been done. Since the early 1970s, some capability has existed in the Atomic Energy Commission (AEC) and later in the Department of Energy (DOE), and in the Department of Defense (DoD) to deal effectively with certain very limited scenarios, but until very recently the de facto national position has been that the threat was too unlikely to warrant concern and/or that nothing could be done about it if it was considered likely.