Five years after United Nations peacekeepers deployed to Ethiopia and Eritrea to help end their devastating border conflict, the mission has been rendered virtually impotent and there are increasing concerns the two countries could return to war.
The latest crisis was sparked by Eritrea's decision this month to ban UN helicopter flights, rendering the mission blind to alleged troop build-ups and movements in the border region.
Night patrols are now impossible, de-mining has halted, troops have withdrawn from 18 out of 40 posts, and the UN says it can only monitor - in a limited way - 45 per cent of the border. There are fears for the safety of UN forces.
In meetings last week in New York, India and Jordan, the largest troop providers, warned that unless the Security Council took effective action, they might have to reconsider their deployment.
Jean-Marie Guehenno, the UN peacekeeping chief, said the impasse cut to the heart of the limitations of such missions: they could only work with the governments' support, and could certainly not forcefully stop two armies going to war.
He was speaking after Ethiopian Prime Minister Meles Zenawi last week accused Eritrea of reinforcing troop numbers in the buffer zone along their border. With UN helicopter flights now banned it is impossible to verify the Ethiopian claims but since December it is known that Ethiopia has moved more of its forces to the border area to prevent, what President Zenawi described as any "miscalculation" by Asmara.
As the stalemate continues, questions are beginning to be asked why, five years after the peace accord, the UN is still there at all. The UN insists it remains an important confidence-builder, as well as an alarm "trip wire" if things deteriorate, but concedes its ultimate success relies on political progress supported by the big powers.
When UN troops first deployed in the region, the operation was seen as a rare classical peacekeeping mission in Africa, dealing with sovereign states and two disciplined armies, rather than the more usual messy internal conflict between warlords and militia.
But it has been blighted by disputes, and deadlocked since the Hague-based international boundary commission ruled in April 2002 that the town of Badme - the war's flashpoint - belonged to Eritrea.
After initially saying it would accept the commission's decision, Ethiopia disputed the ruling, and physical demarcation has been suspended indefinitely.
Addis Ababa says it wants dialogue. But Asmara refuses negotiations until the border is demarcated, saying the international community should force Ethiopia to accept the commission's decision.
Critics say the international community, particularly the accord's guarantors, which include the US, the European Union and the African Union, have failed to push home a political solution.
"For the last three years they have done very little to resolve or address the issue of Badme. If the current trend continues, war is inevitable, and the UN would be forced to pull out," said Ted Dagne, an Africa expert at the US Congressional Research Service.
"It sets a very dangerous precedent, that you can have a wonderful peace agreement and send a UN peacekeeping mission but then it could all fall apart. If they fail to avert another war, what are the implications for the recently signed agreement in Sudan and the UN mission there?"
