"There are better odds that an asteroid would hit Oak Ridge than the likelihood that terrorists would have the access and time to build and detonate an IND [improvised nuclear device]," Y-12 National Security Complex spokesman Steven Wyatt told Los Angeles Times reporter Ralph Vartabedian in response to the concerns of an IND detonation a recently-released POGO report raises (pdf). (Y-12 is located near Oak Ridge, Tennessee; also located nearby is Oak Ridge National Laboratory.)
If what Wyatt says is true, then Oak Ridge must be a magnet for asteroids. Or security experts at the Department of Energy are totally wrong.
More likely though, his dismissal of the IND threat is PR spin more than anything else. The government's own security strategy of access denial--which Wyatt says Y-12 does not meet--is built around the threat of INDs. Moreover, mock attacks by force-on-force adversary teams have shown that a (not-unrealistic) team of terrorists could actually penetrate Y-12 and get to its HEU and build an IND within minutes of the initiation of an attack.
INDs are ridiculously easy to create, according to several esteemed physicists. According to Princeton University physicist Frank von Hippel, "a 100-pound mass of uranium dropped on a second 100-pound mass, from a height of about 6 feet, could produce a blast of 5 to 10 kilotons." By comparison, the blast from the Hiroshima bomb was 13 kilotons. It killed over 200,000 people.
The concern over INDs is based on the government's findings, not just POGO's. Wyatt can spin as much as he wants (and we have to grant him some kudos for the asteroid statement; rarely are government spokepersons so clever), but security experts inside and out of the government find the vulnerabilities at Y-12 and the threat of an IND detonation significant enough to warrant greater security as soon as possible--before the next asteroid hits Oak Ridge, ahem Earth.