How did Eritrea's secession change Ethiopia's access to the Red Sea?

The 1993 secession of Eritrea from Ethiopia fundamentally transformed Ethiopia into a landlocked country, depriving it of its direct coastline along the Red Sea.12

Prior to this, Eritrea served as a vital maritime gateway for Ethiopia. Specifically, the port of Asseb had become a critical hub for the country, handling approximately 70 percent of Ethiopia's import-export trade and housing its first petroleum refinery. Following independence, while Asseb initially remained an open port for Ethiopian trade, the relationship between the two nations became increasingly strained over trade issues and access to these ports.34

This loss of direct sea access created significant economic challenges, as Ethiopia became dependent on transit through neighboring countries for its seaborne trade. The resulting geopolitical tensions, including a border war that began in 1998, further complicated Ethiopia's ability to utilize Eritrean ports for decades. It was not until 2018 that diplomatic relations were restored, leading to agreements to reestablish transportation and trade ties between the two nations.245