I think that the stable countries nearby should be the ones to solve the problem. The people of Zimbabwe would be much more welcoming of troops of a similar culture to theirs than to troops shipped there from half-way around the world who speak a foreign language and look and act completely different. This sort of thing should be orchestrated by the UN, where the countries near to the problem spot are put in charge and given support by the big nations such as the U.S., U.K., Canada, etc. Of course this isn't a perfect world, so the right thing often doesn't happen.