Ethiopia vs. Sudan

Eritrea and Ethiopia agreed to abide by the 2002 Eritrea-Ethiopia Boundary Commission's (EEBC) delimitation decision, but neither party responded to the revised line detailed in the November 2006 EEBC Demarcation Statement; the undemarcated former British administrative line has little meaning as a political separation to rival clans within Ethiopia's Ogaden and southern Somalia's Oromo region; Ethiopian forces invaded southern Somalia and routed Islamist courts from Mogadishu in January 2007; "Somaliland" secessionists provide port facilities in Berbera and trade ties to landlocked Ethiopia; civil unrest in eastern Sudan has hampered efforts to demarcate the porous boundary with Ethiopia; Ethiopia's construction of a large dam (the Grand Ethiopian Renaissance Dam) on the Blue Nile since 2011 has become a focal point of relations with Egypt and Sudan; as of 2020, four years of three-way talks between the three capitals over operating the dam and filling its reservoir had made little progress; Ethiopia began filling the dam in July 2020

the effects of Sudan's ethnic and rebel militia fighting since the mid-20th century have penetrated all of the neighboring states; Chad wishes to be a helpful mediator in resolving the Darfur conflict, and in 2010 established a joint border monitoring force with Sudan, which has helped to reduce cross-border banditry and violence; civil unrest in eastern Sudan has hampered efforts to demarcate the porous boundary with Ethiopia; as of early 2019, more than 590,000 Sudanese refugees are being hosted in the Central African Republic, Chad, Egypt, Ethiopia, Kenya, and South Sudan; Sudan, in turn, is hosting more than 975,000 refugees and asylum seekers, including more than 845,000 from South Sudan; Sudan accuses South Sudan of supporting Sudanese rebel groups; Sudan claims but Egypt de facto administers security and economic development of the Halaib region north of the 22nd parallel boundary; periodic violent skirmishes with Sudanese residents over water and grazing rights persist among related pastoral populations along the border with the Central African Republic; South Sudan-Sudan boundary represents 1 January 1956 alignment, final alignment pending negotiations and demarcation; final sovereignty status of Abyei Area pending negotiations between South Sudan and Sudan