One agency is incapable of managing the role of peacekeeper. Simply because it economically draining. I think what is need is a merger of several organizations to manage difficulties in relations between countres. The U.N, SEATO, NATO, the Red Cross/Crescent, the United Way et al.
One problem is when you create an agency this all encompassing you ultimately end up with limitless red tape. If we could streamline it...the possibility is there to create an effective and fair organization that can administer a large part of the world's conflicts and problems.
Another problem that arises is the fear of a "one world " government. Whether that is a valid fear is up for a debate. Large multi national corporations certainly have a vested interest in keeping a governing body of this kind from forming...for obvious reasons. Unfortunately they have the money to lobby against any kind of such an agency forming.
Of course, left wing groups also fear an agency like this forming because the possibility is there that they could in turn contract out peacekeeping and rebuilding efforts. Thus making the multi nationals even more powerful...thus pushing the gap between rich & poor even further.
No country really seems willing to compromise or give up what it perceives as an advantage, either economic, militarily or politically. Stalemate.
The only way I see to effect change is from within each country. People must demand more of their government. We must remind them...That...they are the caretakers of OUR interests.