The correct answer is: "the division of Korea into two nations after World War II"
The Korean War started in 1950 and lasted until 1950. It was a war fought between South and North Korea, after the partition of the country in these two halves. This conflict reached a global scale as it became one of the proxy wars during the Cold War era. While North Korea was supported by the main powers of the Eastern Communist bloc, the URSS and China, South Korea was supported by the UN and by the US.