Final declaration, dated July 21, 1954, of the Geneva Conference on the problem of restoring peace in Indochina, in which the representatives of Cambodia, the Democratic Republic of Viet-Nam, France, Laos, the People's Republic of China, the State of Viet-Nam, the Union of Soviet Socialist Republics, the United Kingdom and the United States of America took part...
4. The Conference takes note of the clauses in the agreement on the cessation of hostilities in Viet-Nam prohibiting the introduction into Viet Nam of foreign troops and military personnel as well as of all kinds of arms and munitions...
6. The Conference recognizes that the essential purpose of the agreement relating to Viet-Nam is to settle military questions with a view to ending hostilities and that the military demarcation line should not in any way be interpreted as constituting a political or territorial boundary...
7. In order to insure that sufficient progress in the restoration of peace has been made, and that all the necessary conditions obtain for free expression of the national will, general elections shall be held in July 1956, under the supervision of an international commission composed of representatives of the member states of the International Supervisory Commission referred to in the agreement on the cessation of hostilities.
Modern History Sourcebook: The Final Declaration of The Geneva Conference: On Restoring Peace in Indochina, July 21, 1954
The United States did not sign and did not honor the Geneva Agreement of 1954. This is why: "I have never talked or corresponded with a person knowledgeable in Indochinese affairs who did not agree that had elections been held as of the time of the fighting, possibly 80 per cent of the population would have voted for the Communist Ho Chi Minh as their leader."
Source: Dwight D. Eisenhower, Mandate for Change, 1953-56 (Garden City, NY: Doubleday & Compnay, Inc., 1963), p. 372
https://www.mtholyoke.edu/acad/intrel/vietnam/ddeho.htm
The War in Vietnam happened because the United States prevented the ascension of a leader the vast majority of the Vietnamese wanted. The War in Vietnam was tragically futile. It was an expensive losing war fought with a tough resourceful enemy in which the rewards of victory and the penalties of defeat were imperceptible. Vietnam was unimportant to America's economy and to America's economy.
President Johnson sent American ground troops into Vietnam, but President Eisenhower got the United States involved in the first place.