At some point, Butabika joined the Uganda Army, and rose to second lieutenant during the rule of Milton Obote. Over time, dissatisfaction grew among parts in the military about Obote's government, resulting in a conspiracy to remove him from power. Butabika joined the conspirators, and their coup was planned at his house. The initial plan was to blow up Obote's plane at the Entebbe International Airport on 24 January 1971, but Butabika's wife informed her brother-in-law Ahmad Oduka, Senior Superintendent of Police, of the plot. He was supposed to be among those on the plane, and his sister-in-law urged him to stay at home on that day to save his life. Oduka, however, was loyal to the government and informed Minister of Internal Affairs Basil Kiiza Bataringaya. Though the assassination of Obote was prevented, the putschists still managed to launch a coup d'état on 25 January 1971. They overthrew the government, but then became unsure about the further course of action. Amin was initially reluctant to assume the presidency, whereupon Butabika reportedly threatened him at gunpoint to accept his appointment as President of Uganda. Meanwhile, Butabika's wife had fled the capital out of fear that her informing Oduka of the putschists' plan would have repercussions.