The Russian military tried to impose authority by building a series of forts, but these forts in turn became the new targets of raids and indeed sometimes the highlanders actually captured and held the forts. By 1816, Russian engagement with the Circassians made military commanders like General Aleksey Yermolov conclude that "terror" would be effective toward frontier protection instead of fortress construction as "moderation in the eyes of the Asiatics is a sign of weakness". Under Yermolov, the Russian military began using a strategy of disproportionate retribution for raids. With the goal of imposing stability and authority over the whole Caucasus, Russian troops retaliated by destroying villages where resistance fighters were thought to hide, as well as employing assassinations, kidnappings and the execution of whole families. Because the resistance was relying on sympathetic villages for food, the Russian military also systematically destroyed crops and livestock and killed Circassian civilians. Circassians responded by creating a tribal federation encompassing all tribes of the area.