There are war crimes commited by every country or group since the dawn of time. I don't get the point of your question.
u.s, north korea, south korea, and china
South Korea, US vs North Korea, USSR, China
they were involved by sending troops to help south Korea fight north Korea.
No. North Korea did not exist until after World War 2.
Vietnam and Korea .
nope
By attacking the Republic of Korea!
First off, there was no South Korea during world war 1. Korea as a whole was neutral and was not involved in world war 1.
North Korea, South Korea, United States, and the USSR
The British fought in Korea, not Vietnam.
The Korean War was actually a Police Action that involved the United Nations and North Korea. North Korea was Chinese and Russian backed. They invaded South Korea. This argument was the result of the Cold War and the bad feelings from that. Both Countries are really still at war.
The nations that were involved in the Korean war were the US who aided south Korea and the soviet union, who aided north Korea.