In late 1978, Ugandan troops invaded neighboring Tanzania under unclear circumstances, causing the Uganda–Tanzania War. Tanzania responded with a counter-invasion, and Amin's government began to collapse. Oris was one of the few Ugandan officers who remained loyal throughout most of the conflict. By 1979, he had been appointed Minister for Animal Resources and Minister of Lands. On 4 April 1979, Amin organized a four‐member war planning committee which consisted of his most trusted followers, including Oris. By this point, the Uganda Army had mostly disintegrated. After the Fall of Kampala, Oris fled with 3,000 cattle into exile to Sudan. He went on to join the Sudanese Armed Forces as a mercenary, and also became a member of the Former Uganda National Army, a pro-Amin rebel group that fought in the Ugandan Bush War. In the late 1980s and early 1990s Joseph Kony, the leader of the rebel group known as the Lord's Resistance Army claimed to be possessed by the spirit of Juma Oris. It appears he was unaware that Oris was at the time still alive—something which he discovered when the two men eventually met in person.