Federal authorities announced Thursday the biggest eco-terrorism bust in U.S. history, clearing up a series of arsons that plagued the Pacific Northwest from 1998 to 2001. The U.S. Attorney for Oregon, Karen J. Immergut, announced the arrests of six alleged ecosaboteurs from Portland to New York accused of taking part in four arsons attributed to the Animal Liberation Front and the Earth Liberation Front, as well as the vandalizing of power transmission lines. The nine-year investigation cleared up, in order, the June 1998 arson of a U.S. Department of Agriculture building in Olympia; the December 1998 torching of U.S. Forest...