Eritrea's two ports of Masawa and Assab were the main ports used by Ethiopia until the war broke out in 1998.

BBC: Ethiopia rejects Eritrean ports

The port of Assab in the south of Eritrea was used almost exclusively by Ethiopia and since the war, the port has been idle.

BBC: Ethiopia rejects Eritrean ports

And it prevents food for land-locked Ethiopia arriving through the Eritrean ports of Massawa and Assab, from where it could be carried on by rail.

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The two countries hardly became good neighbours, with the issues of Ethiopian access to the Eritrean ports of Massawa and Assab and unequal trade terms souring relations.

BBC: Eritrea profile