Why, and with what success, did the UN intervene in the Korean War?

The Korean War was the first war the United Nations had to face. The new world organization had come into existence a mere five years ago. The UN was established immediately after World War II and replaced the League of Nations. Its goals were to maintain international peace and security and to achieve cooperation in solving international conflicts. The name was coined by President F.D. Roosevelt and officially began January 1st 1942 when 26 countries joined. In attempts to not make the same mistakes the League of Nations made, the UN took action and played a military role in the Korean Wa…