That's my point. The UN is toothless unless the various member states agree to provide resources. Even then, the UN often ends up putting insane restrictions on how they'll be used resulting in their being totally ineffective.
For example, I can remember reading about the experiences of a Canadian officer assigned to a UN peacekeeping unit (can't call what he did "force") in a zone between Israel and Lebanon. All he did was watch the two exchange intermittent fire on each other, helpless to do anything but stay out of the line of fire. UN troops are still there in the "Blue Zone," and still can't do shit to stop Hezbollah firing rockets into Israel or Israel responding with an air strike or artillery fire.
They are useless.