Sudan's army leader, General Abdel Fattah al-Burhan, says the military will not join talks next month in Switzerland aimed at ending more than a year of fighting with the paramilitary Rapid Support Forces (RSF). Al-Burhan made the statement on Wednesday, shortly after the military said he survived a drone strike on a military graduation at the Gibeit army base in eastern Sudan that killed at least five people. "We will not retreat, we will not surrender and we will not negotiate," al-Burhan told troops. "We are not scared of drones," he said at the Gibeit base, which is about 100km (62 miles) southwest of Port Sudan, where the army-aligned government fled after war broke out with the RSF in April last year. The fighting has created the world's largest displacement crisis and killed at least 15,500 people, according to United Nations estimates. Video of the drone attack, verified by the Reuters news agency, showed soldiers marching in a graduation ceremony before a whirring sound can be heard.