From Justin Rood, reporter for Congressional Quarterly:
The Department of Homeland Security (DHS) does not list right-wing domestic terrorists and terrorist groups on a document that appears to be an internal list of threats to the nations security.
[It includes] left-wing domestic groups, such as the Animal Liberation Front (ALF) and the Earth Liberation Front (ELF), as terrorist threats, but it does not mention anti-government groups, white supremacists and other radical right-wing movements, which have staged numerous terrorist attacks that have killed scores of Americans. Recent attacks on cars, businesses and property in Virginia, Oregon and California have been attributed to ELF.