Which conference led to the division of Vietnam into two separate entities?

The division of Vietnam into two separate entities, North Vietnam and South Vietnam, was established during the Geneva Conference held in 1954. This conference addressed issues related to the Korean War and the First Indochina War, specifically focusing on Vietnam's future following the withdrawal of French colonial forces. The Geneva Accords resulted in a temporary military partition at the 17th parallel, with plans for national elections to be held in 1956 to reunify the country. However, these elections were never conducted, ultimately solidifying the division between the communist North and the anti-communist South.

The other conferences mentioned, such as the Yalta Conference, focused primarily on post-World War II European borders and the establishment of the United Nations. The Helsinki Accords addressed European security and cooperation during the Cold War but did not pertain to Vietnam. The Brussels Conference had different objectives related to NATO and European politics, without direct relevance to the situation in Vietnam. Thus, the Geneva Conference is the key event that led to the formal division of Vietnam.