The ELF gained national attention for a series of actions which earned them the label of eco-terrorists, including the burning of a ski resort in Vail, Colorado in 1998, and the burning of an SUV dealership in Oregon in 1999. In the same year the ELA had made headlines by setting fire to the Vail Resorts in Washington, D.C., causing $12 million in damages. The defendants in the case were later charged in the FBI's "Operation Backfire", along with other arsons and cases, which were later named by environmentalists as the Green Scare; alluding to the Red Scare, periods of fear over communist infiltration of U.S. Following the September 11, 2001 attacks several laws were passed increasing the penalty for ecoterrorism, and hearings were held in Congress discussing the activity of groups such as the ELF. To date no one has been killed as a result of an ELF or ALF action since both groups forbid harming human or non-human life. It was then announced in 2003 that "eco-terrorist" attacks, known as "ecotage", had increased from the ELF, ELA and the "Environmental Rangers", another name used be activists when engaging in similar activity.
In 2005 the FBI announced that the ELF, is America's greatest domestic terrorist threat, responsible for over 1,200 "criminal incidents" amounting to tens of millions of dollars in damage to property,  with the United States Department of Homeland Security confirming this regarding the ALF and ELF. 
Plane Stupid then was launched in 2005, in an attempt to combat the growing airport expansions in the UK using direct action with a year later the first Camp for Climate Action being held with 600 people attending a protest called Reclaim Power converging on Drax Power Station in North Yorkshire and attempted to shut it down. There were thirty-eight arrests, with four breaching the fence and the railway line being blocked. 
Radical environmentalism has been called a new religious movement by Bron Taylor (1998). Taylor contends that "Radical environmentalism is best understood as a new religious movement that views environmental degradation as an assault on a sacred, natural world."
Several philosophies have arisen from ideas in radical environmentalism that includes Deep Ecology, Ecofeminism, Social Ecology, and Bioregionalism.
Deep Ecology is attributed to Arne Naess and is defined as “a normative, ecophilosophical movement that is inspired and fortified in part by our experience as humans in nature and in part by ecological knowledge”. 
Ecofeminism originated in the 1970s and draws a parallel between the oppression of women in patriarchal societies and the oppression of the environment.
Social Ecology is an idea attributed to Murray Bookchin, who argued that in order to save the environment, human society needed to copy the structure of nature and decentralize both socially and economically. 
Bioregionalism is a philosophy that focuses on the practical application of Social Ecology, and theorizes on “building and living in human social communities that are compatible with ecological systems”.