What country boycotted the UN debates during North Korean invasion?

The country that boycotted the UN debates during the North Korean invasion of South Korea was the Soviet Union.

The Korean War began in 1950 when North Korea invaded South Korea. The United Nations Security Council condemned the invasion and authorized a military force led by the United States to defend South Korea.

The Soviet Union, a key ally of North Korea, was absent from the UN Security Council meeting when the resolution authorizing military action was passed. The Soviets had boycotted the UN Security Council over the presence of the Republic of China (Taiwan) instead of the People's Republic of China. As a result, the Soviets were unable to use their veto power to block the resolution.

This led to the Soviet Union boycotting the UN debates on the Korean War for a period of time. They argued that the UN's involvement was illegal as the resolution had been passed without their participation.