The Associated Press reports via Yahoo News that the Department of Agriculture has temporarily closed six offices in five states, as a result of terror threats deemed credible. Agencies involved include the Forest Service, the Agricultural Research Service, and the Food Safety and Inspection Service, plus five other agencies not identified in the article.
Probably the most well-known of the six sites is the large ARS research center and library in Beltsville, MD, visible from the DC beltway. On leave from my CA faculty post, I spent 2 years as a management consultant for ARS in the DC area, including some work at Beltsville.
USDA is not a logical target for international terrorists, although they do a modest amount of international work. It could be someone who is really terrified of GMO agriculture.
In the absence of additional information, you should suspect someone or some group here in the States who has a beef with the department or one of its agencies. It's unclear how they identified those six sites to threaten, what they have in common, out of the department's scores of locations.
