Djibouti is asking Secretary-General Antonio Guterres to help peacefully resolve a border dispute with Eritrea following the recent end to that nation’s 20-year border dispute with Ethiopia.

Djibouti’s U.N. ambassador, Mohamed Siad Doualeh, asked Guterres in a letter circulated Wednesday to work with the Security Council to bring his tiny port nation and Eritrea together “with the aim of facilitating an agreement between them upon a mutually acceptable means of peaceful dispute settlement.”

He said Djibouti’s preference would be to refer the dispute “to judicial settlement or arbitration” that would be legally binding.

Djibouti’s appeal to the U.N. chief follows the dramatic diplomatic thaw to one of Africa’s longest-running conflicts that began last month when Ethiopia’s reformist new prime minister fully accepted a peace deal that ended a 1998-2000 border war with Eritrea that killed tens of thousands.

Doualeh recalled that the Security Council imposed sanctions on Eritrea in 2009 “because of its aggression against Djibouti and its refusal to withdraw its troops from the disputed area, and its rejection of all efforts aimed at mediating between the two parties.”