NEW YORK — Well, they say you're known by the friends you keep.

The increasingly outrageous conduct of environmental activists may be costing them some of their gullible friends in academia, the news media and even in Hollywood, but they're still admired by liberal politicians and at least one serial killer.

Unabomber Theodore Kaczynski has written a letter to a magazine applauding young activists who take ``radical direct action to protest the desecration of nature,'' but said he thinks most don't go far enough.

Kaczynski, jailed for life after pleading guilty to a bombing campaign that killed three people and maimed 29, responded to a reporter's query about his relationship to the environmental group Earth First! by saying he was encouraged to see more young people taking action.

But he added that he didn't know much about the group's work, and that from what he does know, the activists aren't going far enough.

``For instance, if you try to stop a logging operation, that's good so far as it goes, but it doesn't go very far,'' Kaczynski wrote in response to questions from a reporter for Gear magazine.

``What we really have to do is get rid of the entire industrial system rather than merely opposing certain specific manifestations of its evil,'' the letter said.

Earth First! is a Eugene, Ore.-based environmental action group best known for its attacks on ranching, timber cutting, and other productive land uses. Their tactics include bombings, arson and "spiking" trees by driving in steel rods that can maim or kill loggers and sawmill operators.

A handwritten version of Kaczynski's letter is being reproduced in the May-June issue of Gear — Penthouse publisher Bob Guccione's new venture — as part of a larger article about eco-terrorism. The magazine targets a young male audience, focusing heavily on pop culture, sports and some in-depth news.

The theme of Kaczynski's letter echoes elements of the Unabomber manifesto he is believed to have authored and sent to some of the nation's largest newspapers before his arrest.

Kaczynski, a scholar-turned-Montana recluse, pleaded guilty to the Unabomber's crimes in part to avoid a trail at which his attorney planned an insanity defense. Kaczynski has adamantly denied being mentally ill.