When they first emerged in the mid-1990s, the environmental extremists calling themselves the "Earth Liberation Front" announced they were "the burning rage of a dying planet."
Ever since, the ELF, along with its sister group, the Animal Liberation Front, has been burning everything from SUV dealerships to research labs to housing developments.
In the last decade, these so-called "eco-terrorists" have been responsible for more than $100 million in damages. And their tactics are beginning to escalate.
Some splinter groups have set off homemade bombs and threatened to kill people. As correspondent Ed Bradley first reported last November, things have gotten so bad, the FBI now considers them the country's biggest domestic terrorist threat.
The biggest act of eco-terrorism in U.S. history was a fire, deliberately set on the night of August 1, 2003, that destroyed a nearly-completed $23 million apartment complex just outside San Diego. The fire was set to protest urban sprawl.
"It was the biggest fire I have ever responded to as a firefighter," remembers Jeff Carle, a division chief for the San Diego Fire Department. "That fire was not stoppable. At the stage that the fire was in when we arrived, there were problems in the adjacent occupied apartment complexes. Pine trees were starting to catch fire. Items on patios were starting to light up and catch fire. And we had to direct our activity towards saving life before we could do anything about the property."
Hundreds were roused from their beds and evacuated. Luckily, nobody – including firefighters – was injured. By the time the fire burned itself out the next morning, all that remained was a 12-foot-long banner that read: "If you build it, we will burn it." Also on the banner was the acronym: E-L-F.
When Carle saw the banner, he says he knew he had a problem.
A problem, because he knew what ELF stood for: the Earth Liberation Front, the most radical fringe of the environmental movement. It's the same group that set nine simultaneous fires across the Vail Mountain ski resort in 1998 to protest its expansion, causing $12 million in damage.
And it is the same group that has left SUV dealerships across America looking like scenes from Iraq's Sunni triangle, their way of protesting the gas-guzzling habits of American car buyers.
The ELF is a spin-off of another group called the ALF, or Animal Liberation Front, whose masked members have been known to videotape themselves breaking into research labs, where they destroy years of painstaking work and free captive animals. In recent years, they've capped off their visits by burning down the buildings. Still, they insist they are non-violent.
"For every arson that I've carried out, there's probably three or four that were not carried out for that fear of injuring somebody," says Rod Coronado, a former ALF leader, who is widely-credited with introducing arson to the cause.
He spent four years in prison for setting six fires, including one at Michigan State University.
Why burn down a building?
"It's simply because after years of rescuing animals from laboratories, it was heartbreaking to see those buildings and those cages refilled within the following days. And for that reason, arson has become a necessary tool," says Coronado.
Coronado says the ALF and ELF operate in small autonomous "cells." He says he usually worked with five or less people.
Asked how after choosing a target, a mission is carried out, Coronado says, "Those are the types of things that take nights and nights and weeks and weeks of reconnaissance to make sure that you know in the one hour that you're going to take action, that there will be absolutely no risk to any living being. The fact that nobody was ever injured in any of the actions that I've been accused of is not a coincidence."
Coronado says these days, he's simply an unofficial spokesperson for the ALF and ELF. And in that role, he travels across the country giving lectures on the groups' philosophies and tactics.
Many in law enforcement believe Coronado is still active in the movement as an organizer and recruiter. He recently found a GPS tracking device under his Jeep, which he believes was planted by the FBI. And, he just happened to have a speaking engagement in San Diego the day after the fire.
Coronado says he knew nothing about the condo complex fire, yet he has traveled around the country and encourage people to do this sort of thing.
"Encouragement through explanation and demonstration of my own actions," says Coronado. "I've showed them how I set fires. I showed them how the ELF and the ALF, what their mode of operation is."
"I'm asking for people courageous enough to take those risks for what they believe in," said Coronado.
60 Minutes was surprised when one of those people, a man claiming to be an active ALF cell leader,to grant what he called "the group's first on camera interview in 20 years," as long as we didn't see his face or record his voice.
He told us that his cell has conducted operations from coast to coast, and every one of them was what he considered to be non-violent because nobody was injured. He said under the mask he is a normal, otherwise law-abiding citizen, and that his friends and family have no idea about his activities. He said he thinks it's "abysmal" that the FBI considers them America's top domestic terrorist threat, because unlike neo-Nazi groups, the ALF has never hurt anyone.