Although many other countries have possessed chemical and biological weapons programs, Rhodesia was one of the few countries known to have used chemical and biological agents. Rhodesian CBW use took place toward the end of Rhodesia's protracted struggle against a growing African nationalist insurgency in the late 1970s. The genesis of the Rhodesian CBW effort emerged as a result of a deteriorating security situation that developed following Mozambique's independence from Portuguese colonial rule.[1][page needed] In April 1980, the former colony became the independent country of Zimbabwe.