In October 1978, Uganda invaded Tanzania, annexing the Kagera Salient. Nyerere decided that Tanzania's response should be not only to push the Uganda Army back into Uganda, but to invade the latter and overthrow Amin. To achieve this, he mobilized tens of thousands of civilian-soldiers to aid the regular army. In January 1979, three Tanzanian battalions pushed into Uganda and leveled Mutukula, slaughtering many of the civilians living there. Nyerere was appalled and ordered measures to ensure the Tanzanians would not attack civilian targets in future. Nyerere also lobbied foreign ambassadors to cut off supplies of oil and weapons to Uganda. Over following months, the Tanzanian army pushed further into Uganda. After they took control of Kampala, Amin and many of his followers fled into exile.