The United Nations General Assembly resolution 498 was approved on February 1, 1951, in response to the intervention of Chinese troops in Korean War.
It was the first time in which United Nations treated a nation as an aggressor.[1]
The resolution had 3 main points:
https://digitalarchive.wilsoncenter.org/document/116196.pdf?v=af553c052ca9889025887077024bc53c?