Somali has submitted its sea border dispute with Kenya to the International Court of Justice.
The triangle of disputed ocean territory stretches for more than 100,000 square kilometres with tests showing potential gas reserves in the area.
Kenya wants the maritime border to go in a straight line east from the land border while Somalia wants it to continue along the line of the land border to the southeast diagonally.
The application comes against a pledge the Kenyan government said it had received from Mogadishu to solve the case out of court.
The Kenyan government must now respond before 27th May, 2016 after which hearings will begin formally.