The United States says it is sending a high-level team to Ethiopia and Eritrea to try to solve their long-running border dispute.
There have been recent reports of troop movements on both sides
US ambassador to the United Nations John Bolton presented the initiative to the UN Security Council.
He said the team of diplomats and military officials would spend 30 days trying to resolve the disagreement.
Last month, Eritrea ordered western UN peacekeepers to leave the buffer zone, amid fears of a renewed conflict.
UN peacekeeping head Jean-Marie Guehenno, who recently travelled to both countries, said the US had "the clout, the credibility to move the process forward".
US assistant secretary of state for African affairs Jendayi Frazer is to head the mission, which is to travel to the region next week, Mr Bolton said.
But BBC Africa analyst Martin Plaut says the key is the presence of a retired general, Carlton Fulford, in the team.
Mr Plaut says this is the last chance for the peace process but he fears it is unlikely to succeed, as neither side seems willing to make the necessary compromise.
UN Secretary General Kofi Annan reported back this month to the Security Council on resolution 1640, which carries the threat of sanctions against both countries if they do not withdraw troops they had sent to the border. He presented them with six options from leaving things as they are to pulling out.
Dec 2000: Peace agreement
Apr 2002: Border ruling
Mar 2003: Ethiopian complaint over Badme rejected
Sep 2003: Ethiopia asks for new ruling
Feb 2005: UN concern at military build-up
Oct 2005: Eritrea restricts peacekeepers' activities
Nov 2005: UN sanctions threat if no compliance with 2000 deal
The two neighbours fought a costly border war from 1997 to 2000, which ended with a peace agreement committing both sides to abide by the ruling of an independent commission which demarcated the boundary.
However, Ethiopia has not withdrawn its troops from the disputed border town of Badme, which the commission awarded to Eritrea.
Eritrea wants the international community to put more pressure on Ethiopia to comply with the ruling.