The arrest of six animal rights activists and environmental radicals last week is the clearest sign in years that law-enforcement authorities now are able to infiltrate the shadowy world of "ecoterrorism."
But the apprehension of four men and two women in five states around the country - all charged with firebombings and other criminal acts committed years ago in the Pacific Northwest - also indicates how hard it is to do that.
While the arrests are significant, many more crimes carried out in the name of protecting animals and the environment remain unsolved. The FBI reports 1,200 such incidents in recent years, ranging from vandalism and the freeing of lab rats to the torching of housing developments and auto dealerships that sell sport utility vehicles. Property damage has totaled more than $200 million, according to members of Congress sponsoring legislation intended to hamper the trend.
Groups such as the Animal Liberation Front (ALF) and the Earth Liberation Front (ELF) usually claim credit for such acts. But as far as law-enforcement officials can tell, there is little organization or structure to the groups. Attackers act alone or in small numbers, adhere to strict security measures in communications and operations, and make use of accessible, unsophisticated equipment like cheap timers.
"Preventing such criminal activity has become increasingly difficult, in large part because extremists in these movements are very knowledgeable about the letter of the law and the limits of law enforcement," said John Lewis, a counterterrorism FBI official, at a congressional hearing. "Moreover, they are highly autonomous."
Among other things, the activists arrested last week are charged with attacks on a lumber company, a meat plant, an electrical transmission tower, and a US Department of Agriculture animal research facility, all taking place between 1998 and 2001.
Over the years, none of the attacks has caused fatalities or major injuries. Environmental and animal rights activists typically say their "direct actions" are meant to avoid harming people and animals.
But threats and other forms of aggressive intimidation directed at researchers, company officials, their families, and others have been escalating.
Jerry Vlasak, a California physician opposed to the use of animals in medical research, is a spokesman for the North American Animal Liberation Press Office. At a recent congressional hearing, Dr. Vlasak insisted that "using any means necessary" to stop people from hurting animals "would be a morally justifiable solution to the problem." When asked if that included killing people, he didn't deny it.
US lawmakers recently proposed legislation targeted at what Sen. James Inhofe (R) of Oklahoma calls "ecoterror groups." It increases penalties for anyone convicted of causing economic disruption or damage, or for placing a person "in reasonable fear of death or bodily harm ... because of their relationship with an animal enterprise."
Meanwhile, courts have not hesitated to impose stiff sentences in such cases. One environmental activist was sentenced to 22 years in prison for burning three SUVs at a car dealership in Eugene, Ore. Two of those arrested last week could face life in prison if convicted of arson and using an incendiary device.
Though attacks by some radical activists continue, officials believe they are better able to prevent or prosecute them.
"We are making progress," the FBI's Lewis told a Senate committee in October.