The suspects, identified as members of the Earth Liberation Front (ELF) and Animal Liberation Front, were indicted Thursday for arson and using destructive devices on targets including a police department, a forest ranger station and facilities in the Vail, Colorado, ski resort.
Federal Bureau of Investigation (FBI) director Robert Mueller called the suspects 'ecoterrorists'.
'Terrorism is terrorism, no matter what the motive,' Mueller said at a news conference in Washington. 'There is a difference between constitutional protected advocacy and violent criminal activity.'
The charges also included conspiracy, attempted arson and destruction of an energy facility.
Eight suspects were arrested before the indictment and three are believed to be outside of the United States, the officials said.
On its website, the Earth Liberation Front distanced itself from those charged, saying it had not 'encorsed, encouraged or approved' the violent actions and that it had no 'membership'.
'Any individuals who committed arson or any other illegal acts under the ELF name are individuals who choose to do so under the banner of ELF and do so only driven by their personal conscience,' ELF said.
The 17 attacks took place in five states between 1996 and 2001, where the targets also included a high tension power line and meat processing companies in Oregon. Wyoming, Washington and California saw similar attacks.
Some investigations went on for over 10 years, officials from the Bureau of Alcohol, Tobacco, Firearms and Explosives said.
The defendants allegedly used improvised incendiary devices made from milk jugs, petroleum products and homemade timers in their attacks.
In October 1998, fires in Vail destroyed a mountaintop restaurant, several chairlifts, and other buildings and shelters causing some 12 million dollars in damage.
The week before the attack a federal judge dismissed a lawsuit by environmentalists seeking an injunction against a planned expansion of the resort.
'The trail of destruction left by these defendants across the western United States caused millions of dollars in damages to public and private facilities,' said Attorney General Alberto R. Gonzales.
