Modern Diplomacy Authors: Yeheys Nardos Hawaz and Chen Xi, PhD* Relations between Sudan and Ethiopia are the most reliable and exemplary in East Africa. Although the two countries have a history of political differences on boundary, they have never considered war as an option. During the 17-year civil war in Ethiopia, Sudan and Ethiopian governments stood in opposition against each other. Despite repeated complaints about the border issue, they had never tried to solve the problem in war. Besides, both have focused mainly on their internal issues which related to the frequent ethnic conflictin Ethiopia and the recent political crisis in Sudan. Also, Ethiopia, Egypt, and Sudan have been embroiled in several diplomatic disputes over the Nile causeway, but Sudan’s humble position was a good neighborly symbol, not hostility. During Ethiopia’s law enforcement campaign in the Tigray region, Sudan began tightening its military presence along the border. More recently, however, Sudanese forces have taken control of several areas. It is undeniable that the war in Tigray has weakened Ethiopia’s control over the border. However, after all, why did Sudan suddenly become embroiled in a border dispute with Ethiopia? Why did the border dispute in Sudan suddenly trigger a military conflict?