Eritrea’s order expelling American, Canadian and European peacekeeping troops along the 600-mile border with Ethiopia is ominous. The order, sent to the United Nations on Tuesday, is a peremptory reaction to the threat by the Security Council to impose sanctions on Eritrea. These were proposed because of its refusal in October to allow UN helicopter patrols over its airspace along the buffer zone that separates thousands of its troops from those of Ethiopia. Already UN vehicles have been banned from night patrols. The UN has vacated 18 of its 40 posts. And this latest measure now deprives the peacekeepers of transport, jeopardising the entire UN presence. Asmara could scarcely have given a blunter signal that it is preparing to resume the senseless border war with its larger neighbour that began in 1998 and cost an estimated 80,000 lives.

The Eritreans’ short-sighted and provocative action stems from frustration that the Ethiopians have not fulfilled all the terms of the precarious peace agreement, negotiated with great difficulty and never fully accepted by either side. In particular, Ethiopia has not withdrawn from Badme, a dusty border town in an area that has few people, little agriculture and vir- tually no intrinsic worth. There is no mechanism for enforcing compliance, and Eritrea has denounced the UN resolution last month as a “recipe for new conflict” because it did not mandate sanctions on Ethiopia. Addis Ababa, predictably, called the Eritrean action “inappropriate and unhelpful” and said it would take “all necessary measures” to defend its sovereignty.

The situation is already tense. Both sides have been building up troops along the frontier for weeks. Civilians in Eritrea are clearly afraid of their Government’s belligerence, and over the past few months thousands have fled to Sudan and Ethiopia, at great danger to themselves and their families. Those caught risk being shot; their families are frequently imprisoned by the Government.

Blame for the tension lies squarely with the political leadership in both countries. Neither Isaias Afwerki in Eritrea nor Meles Zenawi have lived up to earlier hopes that they would lead a new generation of pragmatic, realistic African leaders. President Afwerki is an autocrat who has not held an election since Eritrea gained independence after a 30-year separatist war with Ethiopia. Mr Meles has recently allowed a vote, but this was deeply flawed and troops opened fire on demonstrators. Neither man has earned the premature praise by Western leaders, in particular former President Clinton, with a focus on development, regional co-operation or building democratic state institutions.

A return to war would be disastrous. The Horn of Africa is one of the poorest parts of the world. Drought and natural disasters have aggravated the mismanagement and tyranny of past dictatorship. The two-year indiscriminate slaughter across the barren frontier, an African version of 1914 trench warfare, cost an estimated $1 million a day, and set back hopes for a generation. This must not happen again.