Andrew Auernheimer isn't the kind of internet troll who hides behind a screen name. A notorious computer hacker whose anti-Semitic rhetoric matches the swastika tattooed on his chest, the 31-year-old views online trolling campaigns as a modern form of an age-old political tactic.

"Being offensive is a political act," he told The Associated Press in a phone interview. "If something pushes up against polite civilization, it's for a purpose."

Trolling ( http://apne.ws/2mPU2Gk ) is a calling card of the "alt-right" — an amorphous fringe movement that uses internet memes, message boards and social...