Answer: Attack on South Korea.
Step-by-step explanation:
North Korea staged the attack and accused Seoul of being the first to attack. Because of this, they invade South Korea and break their resistance within days. This led to US and UN involvement in the war. A pivotal moment occurred during the Battle of Pusan. Americans, along with UN troops and the South Korean army, resisted North Korea.
The United States and UN troops have suffered heavy losses but have established a safe zone in the area. Soon, UN troops were granted permission to advance to Pyongyang, defeating North Korean soldiers in a few days. China's entry into the war succeeded in sustaining the North Korean government. Soon after, things returned to their starting point. The Chinese offensive, therefore, influenced the further course of the conflict. Their involvement in this conflict saved the North Korean regime. Even today, China is the most significant international ally of the North Korean government.