The National Terrorist Financing Risk Assessment, published 12th June, includes virtual currencies on a list of "potential emerging" risks as a tool for funding terrorism, stating that bitcoin "may be vulnerable to abuse by terrorist financiers".
The report notes: "Given the attractiveness of virtual currency to conduct illicit financial transactions, the possibility exists that terrorist groups may use these new payment systems to transfer funds collected in the United States to terrorist groups and their supporters located outside of the United States, although the degree to which this presents a residual TF [terrorist financing] risk is unclear."
Full story: http://www.coindesk.com/us-treasury-bitcoins-use-to-fund-terrorism-remains-unclear/