United Nations Security Council Resolution 90 relating to the Korean War is adopted.

United Nations Security Council Resolution 90 adopted unanimously on January 31, 1951, resolved to remove the item "Complaint of aggression upon the Republic of Korea" from the list of matters of which the council is seized.

The Korean War was an armed conflict on the Korean Peninsula fought between North Korea and South Korea and their allies. North Korea was supported by China and the Soviet Union, while South Korea was supported by the United Nations Command (UNC) led by the United States. The conflict was one of the first major proxy wars of the Cold War. Fighting ended in 1953 with an armistice but no peace treaty, leading to the ongoing Korean conflict.