In 2153 an Arctic research team on Earth uncovered frozen cybernetic beings, which revived, assimilated the scientists and escaped in a ship pursued by Enterprise.
The researchers found wreckage and two frozen bodies buried in the ice, debris left from the Borg incursion into Earth's past. Once thawed, the drones assimilated the team, seized a transport and began attacking other ships, while Enterprise followed.
Phlox was infected during the pursuit and used radiation to halt the assimilation. Archer destroyed the stolen ship, but not before the drones sent a message toward the Delta Quadrant. It was not expected to arrive for about two centuries, and the crew never learned who the cyborgs were.