The United Nations Mission in Liberia (UNMIL) has been operating since September, 2003. Current strength is about 15,000 (92 percent are soldiers). Like most UN peacekeeping operations, it's something of an organizational nightmare. That can be seen by the sheer number of nations contributing troops and other personnel. They include; Bangladesh, Benin, Bolivia, Brazil, Bulgaria, China, Croatia, Czech Republic, Denmark, Ecuador, Egypt, El Salvador, Ethiopia, Finland, France, Gambia, Ghana, Indonesia, Ireland, Jordan, Kenya, Kyrgyzstan, Malawi, Malaysia, Mali, Moldova, Namibia, Nepal, Niger, Nigeria, Pakistan, Paraguay, Peru, Philippines, Poland, Romania, Russia, Senegal, Serbia & Montenegro, South Africa, South Korea, Sweden, Togo, Ukraine, United Kingdom, United States, and Zambia. 

This might seem like a recipe for  administrative chaos, but the UN has developed ways to cope. Without saying anything officially, UN commanders know, from briefings and word-of-mouth, which military contingents are more reliable and effective than others. For the most inept troops (and a lot of those are sent off on UN peacekeeping duty), there is plain old guard duty. For the more accomplished troops (from the West, or countries like India or Nepal), there are the most difficult peacekeeping tasks. These usually involve confronting armed groups that refuse to disarm. The prospect of some combat requires troops you can rely on. While peacekeepers are told they are not walking into a war, they are entering an area full of armed, and dangerous, men.

UNMIL costs about $822 million a year to operate. The military commander is a Nigerian general, but most of the staff are a polyglot bunch  from UN headquarters (the better to keep an eye on each other, and keep the corruption under control.)

Liberia is not exactly a good example of how peacekeeping works. Civil war broke out in there in 1989. A year later, West African nations sent in a peacekeeping force. The various factions made, and broke, peace agreements through the 1990s. The West African peacekeepers were not well enough trained, or numerous enough, to stop the fighting. Finally, in 2003, with the various factions exhausted, a larger force, UNMIL, was formed, and sent in to enforce the latest peace deal. So far, this one has held, and most of the armed Liberians have disarmed. But not all. 

Worse, next door in Sierra Leone, there is a similar situation, and a 12,000 man peacekeeping force (UNAMSIL) that costs only $292 million a year. Sierra Leone fell apart in 1991, and it wasnt until 2000 that things had quieted down enough for UNAMSIL to be sent in. 

These two areas, especially Sierra Leone, have been the scene of civil war or tribal conflict, for centuries. Its unlikely that the UN is going to resolve the underlying problems that cause these wars every generation or so.