Ethiopia ? The United Nations reluctantly withdrew American and other peacekeeping staff from Eritrea on Thursday and said it faced an unprecedented crisis in its monitoring of the country’s fragile peace with Ethiopia.

Amid fears of a new Horn of Africa war, the U.N. Security Council on Wednesday bowed to Eritrean demands that all Americans, Canadians and Europeans – about 180 of a force of about 3,300 – leave the U.N.’s Eritrea-Ethiopia peacekeeping mission.

But the council and Secretary-General Kofi Annan made clear that the decision to redeploy the military observers and civilian staff to the Ethiopian capital was just a first step.

Both promised a speedy review of the entire U.N. peacekeeping operation – and one option almost certainly will be to end it and send all members home.

The United Nations established the mission after a 2 1/2-year border war between the neighbors. A December 2000 peace agreement provided for an independent commission to rule on the position of the disputed 621-mile border, while U.N. troops patrolled a 15-mile buffer zone between the two countries.