In 1971 Colonel Idi Amin launched a military coup that overthrew the President of Uganda, Milton Obote, precipitating a deterioration of relations with the neighbouring state of Tanzania. Amin installed himself as president and ruled the country under a repressive dictatorship. In October 1978 he launched an invasion of Tanzania. On 1 November he announced the annexation of the Kagera Salient, an 1800 square kilometre (1118.5 square mile) strip of land between the Ugandan border and the Kagera River. Ugandan troops subsequently pillaged the area they occupied, murdering civilians, stealing cattle, and destroying property, triggering the flight of 40,000 inhabitants southward. Tanzania eventually halted the assault, mobilised anti-Amin opposition groups, and launched a counter-offensive. In January 1979 the Tanzania People's Defence Force (TPDF) seized the Ugandan border town of Mutukula to counter any further threats to Kagera. The TPDF bulldozed homes in the locale and murdered local civilians to avenge the destruction in Kagera. Deeply disturbed by the event, Nyerere subsequently instructed his troops to refrain from harming civilian life and property.