The UN promotes peace? What planet do you live on and how do I get there?
It is easy to criticize...perhaps you could do better...in which case we'll miss you while you go solve the world's problems.
From UN web site:
In accordance with the purposes and principles enshrined in the Charter of the United Nations, the Department of Peacekeeping Operations (DPKO) is dedicated to assisting the Member States and the Secretary-General in their efforts to maintain international peace and security. The Department's mission is to plan, prepare, manage and direct UN peacekeeping operations, so that they can effectively fulfil their mandates under the overall authority of the Security Council and General Assembly, and under the command vested in the Secretary-General.
DPKO provides political and executive direction to UN peacekeeping operations, and maintains contact with the Security Council, troop and financial contributors, and parties to the conflict in the implementation of Security Council mandates. The Department works to integrate the efforts of UN, governmental and non-governmental entities in the context of peacekeeping operations. DPKO also provides guidance and support on military, police, mine action and other relevant issues to other UN political and peacebuilding missions.
Each peacekeeping operation has a specific set of mandated tasks, but all share certain common aims – to alleviate human suffering, and create conditions and build institutions for self-sustaining peace. The substantial presence of a peacekeeping operation on the ground contributes to this aim by introducing the UN as a third party with a direct impact on the political process. In exercise of its tasks, DPKO aims to minimize the many risks to which peacekeepers may be exposed in the field.
Peacekeeping operations may consist of several components, including a military component, which may or may not be armed, and various civilian components encompassing a broad range of disciplines. Depending on their mandate, peacekeeping missions may be required to:
Deploy to prevent the outbreak of conflict or the spill-over of conflict across borders;
Stabilize conflict situations after a cease fire, to create an environment for the parties to reach a lasting peace agreement;
Assist in implementing comprehensive peace agreements;
Lead states or territories through a transition to stable government, based on democratic principles, good governance and economic development.