Ugandan President Yoweri Muvuseni on Monday urged South Sudan rebel leader Riek Machar to agree to a ceasefire or face a military onslaught.

“We gave Machar four days to respond and if he doesn’t, we shall have to go for him [...] to defeat him,” Mr. Museveni said after a meeting in Juba with South Sudan President Salva Kiir.

Mr. Kiir’s former deputy, whose rebel forces started the conflict in mid-December in Juba, has rejected a proposal for a ceasefire by East African leaders and is demanding the release of political allies accused of attempting to overthrow Mr. Kiir.

Mr. Muvuseni said the decision to pursue Mr. Machar had been agreed on by the leaders of IGAD, the Intergovernmental Authority on Development created in 1996 to jointly tackle severe droughts and other natural disasters in the Horn of Africa.

“That is what we agreed in Nairobi,” the Ugandan President said, referring to Friday’s meeting of East African leaders in Kenya.

Fighting has spread to six out of 10 states in the world’s youngest country, killing hundreds and displacing some 100,000 others.

The conflict has also taken on ethnic dimensions, as Mr. Kiir belongs to the Dinka, the largest group in South Sudan, while Mr. Machar is from the Nuer people. Mr. Machar has been in hiding since the start of the fighting.

East African leader said on Friday at the end of summit on the crisis in Nairobi that they would not accept South Sudan’s government being toppled through use of military force.

Uganda has deployed troops at the main airport in the South Sudanese capital Juba to help evacuate foreigners.

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