The leaders of Ethiopia and Eritrea were in Saudi Arabia on Sunday ahead of a meeting described as the signing of a peace accord between the two East African nations.
Terms of the agreement to be signed by Ethiopian Prime Minister Abiy Ahmed and Eritrean President Isaias Afwerki in the Red Sea port city of Jiddah remain unclear.
The United Nations on Friday described the Jiddah meeting as "the signing ceremony of the peace agreement," while Eritrean Information Minister Yemane G. Meskel wrote on Twitter that it involved the "peace agreement of 9 July."
Abiy and Isaias signed a "Joint Declaration of Peace and Friendship" on July 9, ending 20 years of enmity and formally restoring diplomatic relations between Ethiopia and Eritrea.
UN Secretary-General Antonio Guterres also was to be on hand for the meeting Sunday, as will officials from the African Union.
"This is a further agreement helping to cement the positive relations between them," UN deputy spokesman Farhan Haq said Friday.
Landlocked Ethiopia fought a bloody war with Eritrea from 1998 to 2000 over a border dispute that killed tens of thousands of people. The conflict ended in an uneasy peace with Eritrea, which earlier fought a decades-long war of independence from Ethiopia.
Yet that suddenly changed with the election of Abiy as prime minister. A whirlwind of talks suddenly ended the long conflict between the two nations in July, with telephone calls and flights suddenly possible between the two nations.
It was particularly surprising for Eritrea, a closed-off nation of 5 million people ruled by Isaias since 1993. Eritrea's system of compulsory conscription that led thousands of Eritreans to flee toward Europe, Israel and elsewhere. Ethiopia is home to 105 million people.
The signing ceremony Sunday in Saudi Arabia also highlights the growing importance Gulf Arab nations put on East Africa amid the Saudi-led war in Yemen.
The United Arab Emirates, also believed to have played a part in talks between Ethiopia and Eritrea, has been building up a military presence in the Eritrean port city of Assab.
The strategic Bab al-Mandeb Strait, which sits off Eritrea and neighboring Djibouti, links the Red Sea and the Suez Canal with the Gulf of Aden and ultimately the Indian Ocean.
Dozens of commercial ships daily transit the route, just 16 kilometers (10 miles) wide at its narrowest point.