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, a 1,800 square kilometre (700 square mile) strip of land between the Ugandan border and the Kagera River. The Uganda Army subsequently pillaged the area it 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, expelling the Ugandans from its territory. On 22 January 1979 the Tanzania People's Defence Force (TPDF) seized the Ugandan border town of Mutukula to counter any further threats to Kagera. The Tanzanians then constructed an air strip in the locale so transport aircraft could resupply the troops at the front lines.