During the Dominion War, the Klingon Empire managed to procure several samples of polaron torpedoes. Though some of these were taken from the wreckage of Jem'Hadar warships left on the battlefield, this did not give them to the breakthrough necessary to begin building their own rudimentary polaron torpedo models. Rather, they were procured by an elite strike force sent into Cardassian space with the mission of attacking a Dominion communications relay on the border. The small base was not a relay, however, but a temporary storage location for ship parts intended to be used for repairs of other nearby fleet assets.
The looting of these technical models coupled with other information gained from wreckage and prisoners of war allowed the Klingons to demonstrate their first polaron torpedo weapon as early as 2378. These weapons quickly went into production, but the production process was still difficult and few units of acceptable quality were produced for anything more than limited deployment in the fleet.
A variant of the Fek'Lhr Strike Cruiser was the first Klingon unit to mount the polaron torpedo. Replacing its heavy photon torpedoes for polaron torpedoes, it was believed that the ability to pierce enemy shields would make up for the lower total damage.
Klingon understanding of polaron torpedoes and the principles behind them have kept polaron torpedoes from entering general service. Nonetheless, a slow stream of polaron equipped ships such as the Fek'Lhr Polaron Cruiser continued to leave Klingon shipyards for service in the Klingon Defense Forces.