Final answer:
The Korean War was started by the invasion of South Korea by Communist North Korea, with the goal of reunifying the peninsula under Communist rule. The United Nations, led by the United States, responded by denouncing the invasion and sending troops to assist South Korea. The war ended in a stalemate.
Step-by-step explanation:
The Korean War was started by the invasion of South Korea by Communist North Korea, led by Kim Il Sung, on June 25, 1950. North Korea's goal was to reunify the Korean Peninsula under Communist rule. The invasion quickly captured the capital of South Korea, Seoul, and the United Nations (UN) responded by denouncing North Korea's actions and calling for a military response.
The UN, led by the United States, sent troops to assist South Korea in defending against the North Korean invasion. The Soviet Union, a permanent member of the UN Security Council, abstained from vetoing the action, indicating possible approval. The Korean War is often seen as an escalation of the Cold War between the Soviet Union and the United States.
Ultimately, the Korean War ended in a stalemate with no victor. The division between North and South Korea remains to this day, with the Korean Demilitarized Zone (DMZ) separating the two countries.