A more extreme example of long-term UN failures seems to be the Israeli-Palestinian conflict. In fact, there have been charges that the UN is actually making the situation much worse by being a part of the problem.
Below are the thesis and conclusions of a detailed exploration of the role of the UN in fostering peace between Israeli and Palestinians, or in hindering and derailing the possibilities of peace.
"Despite the “Zionism-is-racism” resolution having been annulled, these [UN] offices, agencies, and committees
The article ends with the following conclusion
For the full article, and a chance for you to explore and evaluate the conclusions, see: