...nothing...
The UN fought in Korea.
Member countries of the UN supplied troops and war materials to aid South Korea.
General MacArthur was Commander in Chief of UN Forces in the Korean War. He is thought to be responsible for the continued existence of South Korea.
Australia sent 17,000 men to the Korean War.
See website: Korean War
The S.Koreans asked for the UN help.
The UN.
UN
The UN (United Nations).
money lol
to clear south Korea from occupation by north Korean and Chinese troops
It was an undeclared war.