The Department of Homeland Security has released separate reports this year regarding first left wing and now right wing terrorism. Secretary Napolitano has drawn heat from some on the right for her concern that disaffected veterans might be prone to lash out at the government. She responds by mentioning her involvement with the prosecution of the last disaffected veteran to do so.
It's worth noting that the left wing report was the product of the DHS under the Bush Administration and the right wing report under the Obama Administration. One one hand we could argue that each side is trying to tar the other as unruly extremists, but on the other hand, is it not unreasonable to believe that left wing groups are more likely to strike against a conservative administration and vice versa?