The United Nations announced that a peacekeeping force completed its first mission to determine Sudanese military forces left a disputed border area, UPI reported. South Sudan and Sudan agreed to pull their forces from the border and establish a demilitarized zone. U.N. Undersecretary-General for Peacekeeping Operations Herve Ladsous said peacekeepers completed their first verification mission for the disputed oil-rich area of Abyei. "This first joint verification mission by Sudan and South Sudan is an important first step toward implementing all security arrangements between the two countries," he said in a statement. "There's more to do and it is essential for long-term peace in the region that both countries build on this success." The U.N. Interim Security Force for Abyei confirmed there were no national forces inside the 14-mile demilitarized zone. South Sudan gained independence from Sudan in 2011 under the terms of a peace deal that ended civil war. Both sides nearly went to war last year over disputed oil territory. "Both parties have begun to withdraw from the Safety Demilitarized Border Zone, which they are obliged to complete by April 5," Ladsous said.