Djibouti and Eritrea have been in conflict since June 2008 when their troops fought along the Djibouti–Eritrea border. The conflict revolves around the location of the border and sovereignty over the strategically located Doumeira Islands and adjacent reefs. In 2010 Qatar brokered a mediation agreement and began to implement it, but withdrew in 2017 without notifying Eritrea and without providing reasons to either country. The dispute raises a number of international law issues. This article focuses on the validity and application of three relevant colonial treaties (from 1900, 1901 and 1935) that defined the boundary, one of which (the 1935 Treaty) did not enter into force. Issues relevant to the determination of the borderline and sovereignty over the disputed islands and the unique challenges that may arise are discussed in light of the colonial treaties, relevant International Court of Justice jurisprudence and other international law principles, particularly uti possidetis juris.
