South Sudan rebels claimed Tuesday that they had again seized control of the strategic town of Bor as Uganda’s president threatened military action if there is no ceasefire in place by the end of Tuesday. South Sudan President Salva Kiir insisted he would not sign a power-sharing agreement with rebel leader Riek Machar, who has allegedly joined forces with army defector Peter Gadet. “These men have rebelled,” Kiir said. “If you want power, you don’t rebel so that you are rewarded with the power.” A United Nations spokesman could not confirm if Bor had been seized, but did say fighting had broken out at daybreak. Machar’s troops had overtaken Bor in December, but lost control just before Christmas. At least 1,000 people have died in fighting in the last two weeks.