The Esterians were the population of a colony of the United Federation of Planets.
Fearing a economic crisis, they built a fake Klingon D7-class warship and sent it to attack targets such as the USS Enterprise (NCC-1701). The plan was to start a new conflict that would profit the Esterians by allowing them to trade arms. They had the means to obtain a Romulan cloaking device, one of which they fitted to the warship. However, Captain Kirk of the Enterprise and Captain Kargh of the IKS Dark Destroyer exposed this plot. (Star Trek: New Voyages: "To Serve All My Days")