The U.N. Security Council has threatened Ethiopia and Eritrea with sanctions if either side uses force to settle their border dispute. The Ethiopia/Eritrea issue is being watched as a test of the Security Council's ability to intervene successfully in regional disputes.

The resolution adopted unanimously Wednesday contains warnings to both sides. It expresses "grave concern" about Ethiopia's failure to accept a boundary agreement reached in 2000, and demands that Eritrea lift restrictions on U.N. peacekeepers in the region.

The measure calls on both sides to reduce force levels along the border to what they were before tensions rose last month, and holds out the possibility of economic sanctions if either side fails to comply. 

Washington's U.N. ambassador, John Bolton, said the resolution accomplishes important objectives.

"It demands that Eritrea not use the existence of the peacekeeping force as leverage in the dispute over the border," he said.  "And that's important because one of the problems longstanding U.N. peacekeeping operations have is that they risk becoming part of the problem. And what we want to make clear is that it should not be acceptable that the peacekeeping forces become part of the problem."

The U.S. envoy noted that the resolution also demands that Ethiopia abide by the boundary settlement of 2000, which gave rise to creation of a U.N. peacekeeping force for the region. He said the measure approved Wednesday will be an important test of the Security Council's effectiveness in addressing the causes of regional disputes.

"This is very important for the Security Council to see this through to a successful conclusion," he added.  "Otherwise, people will look at this and say the U.N. Security Council can't resolve a border dispute between Ethiopia and Eritrea. So this is a, for us, a potential pivot point to move beyond the immediate circumstances and to try and get to a real resolution of the underlying issue."

Both sides moved troops to the border last month after Eritrea severely restricted the movement of U.N. peacekeepers on its territory. The peacekeeping mission reported last week that its surveillance ability had been cut by more than 60 percent.

This week, the United Nations ordered dependents of staff members in Eritrea to leave because of heightened tensions.