It was the introduction of a new currency by Eritrea in 1997 that gave the first indications that all was not as it seemed between the two Horn of Africa neighbours.

Until then relations between Ethiopia and Eritrea had appeared to be excellent. For the West, Ethiopia's prime minister, Meles Zenawi, and the Eritrean president, Isaias Afwerki, were a new type of African leader who, it was hoped, would help bring about an African renaissance.

At home they were often described as being like brothers. The Eritreans helped the Ethiopians overthrow the Mengistu regime, and, in 1993, gained their own long-fought for independence.

Until 1997 Eritrea had kept the Ethiopian currency. When it introduced its own, citing economic reasons, the relationship started to look shaky.

The long border shared by the two countries is in places mountainous, rocky and desolate. It has never been properly delineated.

Until last year that didn't seem to matter. Ethiopians seeking work crossed easily into Eritrea. Tens of thousands of Eritreans lived in Ethiopia.

Ethiopian and Eritrean officials held occasional committee meetings to discuss the issue, but these appeared to the outside world as cordial and unproblematic.

Maps and missiles

The border line was based on old colonial maps drawn up by the Italians. Suddenly the maps became the focus of a crisis.

Fighting broke out in May 1998 an area known as the Badme triangle, a 400 square km triangle of land. The Ethiopians, who administered it, said the Eritreans had invaded and they demanded their withdrawal.

Ethiopian militia are ready for action against their neighbours

Eritrea admitted that its forces had entered the area, but claimed that they were taking back land which belonged to Eritrea. The pattern of claim and counter claim was repeated at several more points along the border.

In Addis Ababa, the ruling Ethiopian People's Revolutionary Democratic Front said Ethiopia would not begin negotiations until Eritrean forces pulled back from its land. Eritrea said this was impossible because the land was Eritrean. Deadlock was reached.

There is still some bafflement among analysts as to why Ethiopia and Eritrea allowed the situation to deteriorate so far. Economically both seemed to have a lot to lose.

Ethiopia, which used the Eritrean ports of Massawa and Asab, immediately mounted a blockade and diverted its ships to Djibouti.

While this has caused economic damage to Eritrea, thousands of Ethiopians have also lost a place to work.