U.N. Secretary-General Ban Ki-moon attended the signing in Ethiopia of a deal brokered by 11 African countries to help ensure stability in the eastern DRC.
"This agreement is only a beginning," U.S. Ambassador to the United Nations Susan Rice said in a statement. "States in the region must now work to elaborate detailed agreements that address the root causes of the cycle of violence."
About 800,000 civilians were displaced by fighting that began in May when the rebel March 23 Movement started a mutiny, accusing Kinshasa of reneging on a peace deal that saw former rebels integrated into the national military.
M23 in late 2012 captured Goma, the capital of North Kivu province, but withdrew.
British Minister for Africa Mark Simmonds was more optimistic, saying he welcomed the regional coordination with Ban and other members of the United Nations.
"This agreement offers real hope to the people of the region for a secure, stable and economically sound future," he said in a statement. "The U.K. is committed to playing a positive role in its implementation."