The Khitomer Accords describe two historic peace treaties between the United Federation of Planets and the Klingon Empire signed in 2293 on the Klingon colony world of Khitomer. The accords ended decades of hot and cold war between the two powers and laid the foundation for future cooperation and alliances.
The initial signing was motivated by the Klingon's dire ecological situation after the explosion of their main energy source, the moon Praxis. Although a conspiracy including Federation members, as well as Klingons like General Chang and Romulan Ambassador Nanclus, tried to sabotage the talks, the crews of the U.S.S Enterprise-A and the U.S.S. Excelsior were able to thwart the attempt.
In 2372, the Klingon Empire formally withdrew from the Khitomer Accords due to the Federation's protest against their preemptive invasion of the Cardassian Union. A Founder posing as General Martok claimed the Cardassian government to be under the influence of the Dominion at that time and pushed for the attack. A short Federation-Klingon War followed as the Empire went on to reclaim the Archanis Sector, but the Accords were reinstated only one year later in light of the looming Dominion threat and "General Martok" being exposed as a Changeling.
In 2399, Chancellor J'mpok withdrew the Empire from the Accords yet again, this time due to the Federation's massive protest against the Klingon-Gorn War. A prolonged Federation-Klingon War would soon follow and not be ended until 2410, when both powers realize they have to face the threat of the Undine and the Iconians together .