The Temporal Cold War refers to a conflict involving numerous time-traveling factions in various time periods, each attempting to alter history to its own benefit. (Star Trek: Enterprise) Based on the quantum physics theory of multiple quantum realities, the manipulations of these factions may have created a potentially infinite number of alternate timelines, and the timeline considered "correct" is uncertain. (TNG: "Parallels"; Star Trek)
The Dominion War had become a battleground for the Temporal Cold War. During the Betreka Nebula counterstrikes, ships from the future emerged in the hope of influencing the battle in the Dominion's favor. These ships, however, could only exist in the past for a very limited amount of time. For that reason, this faction's most difficult tasks were carried out by 24th century proxy agents. A cohort of "Future Guy" communicated orders to Sindareen leader Tor Vot. Tor Vot revealed tactical information to the Dominion in return for access to valuable minerals believed to benefit the Sindareen economy. This included the Dominion invasion of Betazed. (Star Trek: Lambda Paz: "The Tides of War, Part I")
In 2411, Commander Reshek Taryn referred briefly to a multifactional time war that had created so much temporal instability it finally erased its entire timeline from existence. (Bait and Switch: "Brother on Brother, Daughter on Mother")
- This strongly suggests that the Temporal Cold War simply did not take place in Bait and Switch's primary timeline.
In the mirror universe, one of the Temporal Cold War's focal points was ISS Enterprise (NX-01). Suliban agents of Future Guy frequently abducted First Officer Jonathan Archer, much to the jealously of Maximilian Forrest, the actual captain of Enterprise. In 2153, Future Guy ordered Silik to abduct Archer to warn him that the Xindi were behind the recent attack on Earth. (Before In a Mirror, Darkly: A Crisis on Earth)