Who: Korea, United States, and other countries.
What: led themselves into a 3 year war.
Where: north and South Korea.
Why: arguing about communism.
Summary: 1950, the Koreans in Korea did not get along with the communism and all this arguing eventually sent them to the Korean War. Involving Korea US and a few more countries. And in 1953, the war ended. But North Korea is still just really cruel and abusive.