After World War II, who controlled North Korea? South Korea?

Hint: Allied officials battling Japan during World War II debated Korea's destiny after Japan surrendered. The leaders agreed that Korea would be freed from Japanese authority, but that it would be placed under international trusteeship until the Koreans were deemed ready for self-government. Much about Korea's future was left undetermined beyond this very hazy deal.

Complete answer:
Japan was still occupying Korea at the time, but it withdrew when two leaders emerged: Syngman Rhee and Kim Il-Sung. Korea was controlled by the Japanese for a brief time after WWII ended before being liberated. Now there were two people claiming to be the leader of Korea, but they were actually the leaders of North Korea and South Korea, respectively.

North Korea - In North Korea, we had Communist Kim Il-Sung, who was inspired by Mao Zedong's communist invasion of China in 1949 and aspired to unite his country under communist ideals as well.

South Korea – In the south, we had Syngman Rhee, a hardline anti-communist who, while not necessarily more democratic than his northern counterpart, was vehemently anti-communist.
The interests of these two individuals would eventually collide when the North invaded the south in 1950, assisted by the Soviet Union, forcing a UN reaction and the start of the Korean War.

Note: The Democratic People's Republic of Korea (North Korea) and the Republic of Korea (South Korea) haven't always had the tense and contentious relationship that they have now. In actuality, the two countries' separation is a comparatively recent occurrence. Korea had been united in language, culture, and politics for nearly a millennium until World War II.