From Wikipedia:
https://en.wikipedia.org/wiki/Alien_Agent
Rykker is an intergalactic warrior trapped on Earth, constantly fighting a gang of ruthless aliens known as The Syndicate, an alien fifth column plotting to take over the planet. The film opens with a high speed chase, with Rykker killing several syndicate agents.
Saylon is a top syndicate leader who crash-lands on Earth. His mission is to build a wormhole portal between Earth and his home planet - allowing a full-scale invasion of the Earth. Isis is the Syndicate's sexy and ruthless leader. During a series of robberies for parts to build the portal, Isis becomes determined to destroy Rykker.
Fifteen-year-old Julie's family was killed when a truck carrying materials for the portal was hijacked. Left alone in the world, she plots to avenge her family. Julie and Rykker hook up, though he tries to leave her behind for her own safety. But she keeps showing up, even saving Rykker's life one time. They go on a cross country journey, with Isis and her army in pursuit. The final showdown inside a nuclear reactor, has Rykker and Julie battling Isis, Saylon and their army of killers in an attempt to destroy the portal and stop the invasion.