By December 1991, when the Soviet Union ceased to exist and Azerbaijan formally became an independent state, despite Mutallibov's presidency Aliyev independently governed Nakhchivan. Early 1992 was marked by increased violence in the First Nagorno-Karabakh War with the fall of Shusha, the last Azerbaijani-populated town in Nagorno-Karabakh. These events resulted in the resignation of Mutallibov and the subsequent rise to power of the Azerbaijan Popular Front led by Abulfaz Elchibey. During Elchibey's one year in power, Aliyev continued to govern Nakhchivan without any subordination to the official government in Baku. The attempt by the Popular Front's Minister of Interior Isgandar Hamidov to forcibly overthrow Aliyev in Nakhchivan was thwarted by local militia at the regional airport. During the same period, Aliyev independently negotiated a cease-fire agreement in Nakhchivan with the then-President of Armenia, Levon Ter-Petrossian.