Eritrea President Isaias Afwerki has blamed the US for a border conflict with Ethiopia that killed an estimated 70,000 people between 1998 and 2000.
Djibouti has accused Eritrea of occupying a stretch of disputed territory along their shared border, days after Qatar peacekeeper troops were withdrawn from the site.
Eritrea claims more than 200 Ethiopian troops were killed in the latest border clash between the two countries.
The UN International Court of Justice has scheduled a hearing into the maritime border dispute between Kenya and Somalia for September.
Sudan has denied accusations from neighbouring South Sudan that it carried out fresh airstrikes in the Upper Nile Region.