Once again, it depends on the situation.
I can give you an excellent example of my experience in Burundi. Remember, I was there in 2004, when the UN mission was launched and the Security Council resolution was passed. However, the process was initiated by the former president of Tanzania, whose name escapes me at the moment. No wait. Now I remember. His name was Julius Nyerere. I don't know how I could have forgotten that because he is one of my heroes. He was the leader of a country like Tanzania and he decided that peace was the most important thing. He welcomed hundreds of thousands of refugees from Rwanda and Burundi to his country. After handing his authority over to his successor, he initiated the peace process for Rwanda and Burundi. That continued for 10 or 15 years. It was the African regional group's support for the peace process that really put pressure on Burundi in a way that the UN was unable to do.
Other organizations therefore have a role to play. The UN is central, but the support of countries in the region is vital. It is impossible to continue without it.