By Jonah Fisher BBC, Ethiopia-Eritrea border

When the United Nations mission was first sent to Ethiopia and Eritrea it was envisaged that their stay would be a short one, charged with keeping the two sides apart while an independent Commission ruled and then built their common border.

Demarcation should have begun here this month

But with Ethiopia having rejected the ruling that the symbolic town of Badme belongs to Eritrea the peace process has now reached what the UN calls "an impasse".

At $250m a year, the peacekeeping presence does not come cheaply, and many are now fearing that their stay is going to turn out to be a lot longer than was first intended.

October in the border's Eastern Sector was the latest time and place where demarcation of the border was supposed to start.

Six hundred and fifty Kenyan soldiers are stationed in the sector, patrolling the security zone and preparing the ground in anticipation of demarcation beginning.

Heat

Living conditions for the Kenyan troops are among the most challenging of any UN peacekeeping mission in the world.

The Eastern sector is a hot volcanic desert, with few settlements outside the port of Assab.

The peacekeepers are costing a lot of money

"It is so dry and the sun is so hot. Temperatures are very high, sometimes over 50 degrees," said Corporal John Otiatoh.

"It is one of the most difficult places I've worked in because in Kenya we don't have very severe condition like this," said Sergeant Gore who's been stationed in Assab for over seven months.

"There are no trees around, there is not much vegetation and generally this is a very, very dry area," he said.

Relations between Ethiopia and the Boundary Commission are now so bad that diplomats in Asmara are openly talking about them packing up their surveying equipment and leaving before the year is out.

Addis Ababa have asked the Security Council for someone else to rule on the symbolic village of Badme - calling the decision to award it to Eritrea "illegal and unjust". It's an idea the Security Council rejected outright.

Demarcation

"To tell you the truth I wouldn't mind if demarcation begins next month, or in December or even in January, as long as it begins, as long as we plant the first pillar," says the head of the UN mission Ambassador Legwaila Joseph Legwaila, "Because the planting of the first pillar will say to the world that demarcation has begun."

Since Ethiopia rejected the Boundary Commission in September - Eritrea's position has been consistent. It will not engage in dialogue on the issue of Badme and wants the international community to pressurise Ethiopia into accepting the decision.

"The issue is not just the delay in demarcation but what appears to be at stake now is the entire Algiers Agreement itself," says Yemane Gebremeskel, the head of the Eritrean President's office.

Ethiopia does not accept the awarding of Badme to Eritrea

"It appears to be non existent or Ethiopia seem to be violating it. And the basic question is why is this being tolerated. We have a situation where the international community has everything at its disposal but is simply not applying those instruments."

With positions hardening and the visit of a US envoy having passed without any visible signs of progress the UN is having to start thinking about how long it will stay if the impasse remains.

As other missions in Africa and elsewhere occupy more troops and funds a long-term presence here is something they are desperate to avoid.