My review was written in June 1986 after watching the movie on Trans World Entertainment video cassette.
"Thunder Warrior" (a/k/a "Thunder") is an okay Italian action picture, benefiting immensely from gorgeous Arizona locations in Monument Valley, the Grand Canyon and environs. Released theatrically overseas, the shot-in-1983 opus debuted on video cassette domestically, with a sequel "Thunder 2" currently in production.
Mark Gregory portrays Thunder, a young Navajo Indian who returns home to find that the tribal burial ground is being destroyed to become the site of an observatory, breaking a treaty signed 100 years ago by his grandfather. After starting a fight on the construction site with a worker named Thomas (Antonio Sabato), Thunder sits in at the office of Sheriff Cook (Bo Svenson). Brushed-off by Cook, he shifts his sit-in to the local bank that is financing the project and is promptly escorted out of the county by the cops.
Subsequently beaten by Thomas and his coworkers, and then treated to police brutality by Deputy Barry (Raymond Harmstorf), Thunder arms himself and becomes a mini-"Rambo" out of "First Blood". He survives, hence the sequel, and is established as a local folk hero after numerous encounters with the police and rednecks who try to hunt him down.
Filmmaker Fabrizio de Angelis (who likes to use the pseudonym "Larry Ludman" when directing), delivers fine stunts and chases, but overdoes slow motion to stylized violent scenes. Western-flavored music by Francesco De Masi is a plus, though film's main draw is its beautiful locations. Typically for an Italian visiting production, interiors were lensed back in Rome.
Star Gregory is good as the sullen Indian, a big improvement on his campy thesping in De Angelis' production of "1990: The Bronx Warriors".