Vosk was the leader of the Na'kuhl, a faction in the Temporal Cold War. Originating from the 29th century, Vosk was strongly opposed to the Temporal Accord, believing it was his right to use time travel for the benefit of his race.
After the entire time-travelling section of the Na'kuhl fleet were immobilized by humans, Vosk was met with Ghrath: who reported that the time-travelling ability within the Na'kuhl's grasp were lost in the immobilization. It was then he and Grath developed a stealth-time travel in order to infiltrate Earth in the 1940s for revenge. (Star Trek: Phoenix-X: "Temporal Doom! Part II")