Why did the Korean War happen?

Question

I have a test on it soon and I lost my notes and the reason is not clear. 10 pts to best answer :)

Answer 1

The Korean War, occurring between June 25, 1950, and a cease-fire on July 27, 1953, was a war fought in Korea that was divided by the post-World War II Soviet and American occupation zones, with large-scale participation by other countries. The war began with the invasion of capitalist South Korea by forces in Communist North Korea in 1950 and ended as a stalemate between the sides in 1953.

The principal support on the side of the North was China, with limited assistance by Soviet combat advisors, military pilots, and weapons. South Korea was supported by United Nations (U.N.) forces, principally from the United States, although many other nations also contributed personnel. When the conflict began, North and South Korea existed as provisional governments competing for control over the Korean peninsula after the Division of Korea.

In South Korea, the war is often called 6·25, from the date of the start of the conflict or, more formally, Han-guk Jeonjaeng (Korean: 한국전쟁, literally “Korean War”). In North Korea, it is formally called the Fatherland Liberation War (Korean: 조국해방전쟁). In the United States, the conflict was officially termed a police action — the Korean Conflict — rather than a war, largely in order to avoid the necessity of a declaration of war by the U.S. Congress. However, it is more commonly referred to as the "Korean War." The war is sometimes referred to outside Korea as “The Forgotten War” because it is a major conflict of the 20th century that garners far less attention than World War II, which preceded it, and the controversial Vietnam War, which succeeded it. In China, the conflict was known as the War to Resist America and Aid Korea (抗美援朝), but is today commonly called the “Korean War” (朝鮮戰爭, Chaoxian Zhanzheng).

Answer 2

Korean war happened because the North Koreans invaded South Korea for reunification.

Answer 3

The Korean war started because the Communist north invaded south Korea trying to re-unify it under a communist regime.