Compounding the inability of the United Nations to administratively and conceptually deal with New Wars, the UN lacks any sort of hard military power necessary for peacekeeping operations. Many states simply refuse to contribute military power to the UN missions out of a general distrust to the UN and NGO’s in general. It has been noted that UN peacekeepers “are traditionally too lightly armed to outfight the combined forces of every regional warring faction in the mission area. Consequently, they exercise no real coercive or punitive power” . The top contributors to UN Peacekeeping missions are in fact Bangladesh (10,736 personnel), Pakistan (10,691), India (8,935), Nigeria (5,709) and Egypt (5,458) . This is an interesting situation, because the top military contributors to the UN are states that are very rarely known for their military prowess.....
I believe that focussing on the military capacities is a bias. Not that it does not count but because it is not the real issue. Cause, as I wrotte before, it works on paper.

The problem is not really the troops’ quality. The main issue is the distance between the mandate and its application. The first problematic is the chain of command. Troop contributors’ countries do not surrender over the UN their chain of command. Therefore you have a UN chain of command with troops who obey to their national chain of command. And because it is a sovereignty issue no one is questioning the non implementation of the mandate by X, Y or Z. You just deal with it. Therefore you lose immediately nearly 90% of your combat capacities. (When they want and there is political will, Indians and Pakistanis are very effective. Bangladeshi... It's another story.)

Talking about DRC, when a 6 battalions (including armored infantry, special ops and paratroopers with air support and artillery… from India and South Africa mainly!) strong force tells you: they cannot defeat 300 armed men… Then you know it is political and not military.

I have witnessed several UN/blue helmets deployments and there is a pattern in how they become ineffective on the ground:
- 1st phase you send for 3 month (max 6 month, if it is high profile domestic issue) highly trained troops from western countries to settle the dust. (works most of the time. Or it is skipped because UN are too slow and NATO already did it)

- 2nd phase, you send troops with average/good military capacities with a clear mandate adapted to a political and military situation. (all ready you have lost most of your combat capacities and you count on deterence only. Mainly because you fright the other parties with your equipment.)

- 3rd phase you change nothing in the mandate, what ever changes happen in the political or military context. (You do not adapt therefore you are obsolete)

- 4th phase you send crappy troops because there no one to go in that mud place and you give them a weak mandate. (you're plan is to leave as soon as possible so you task your force with no mission, may be patroling with armored vehicles, to be able to report a success. Sucess = I reported I did XX patrols in a month so I completed successfully my mission. I do not even have to actually do the patrols, just to report I did it.)

I witnessed that in DRC, Chad, Sudan… In the end, it’s a circus.
I once worked with a Navy commander who was fresh from naval academy in a semi desertic area, commanding conscripts from Army with lieutenants from Air-force. How do you expect such force to do something else than show of force? (That was Sudan by the way)

A Canadian friend of mine was telling me they call the UN missions “Gucci missions”. It tells what it tells: it’s comfortable camping is a crappie place with or without guns.

And as David rightly pointed: it's peace keeping missions, not combat missions. (Even peace enforcement are not combat missions). The last time the UN fought wars, it was Korea and Shaba in Zaire. In the end they won. But it was neither peace keeping or enforcement missions, at that time the mandate was just: win the war.