Final answer:
South Vietnam broke the peace agreement due to dissatisfaction with the terms and the lack of support from the United States.
Step-by-step explanation:
The peace agreement that ended the Vietnam War was ultimately broken by South Vietnam. Although the Paris Peace Accords were signed in 1973, the cease-fire agreement collapsed just a few months later. North Vietnam launched a full-scale invasion against South Vietnam in 1975, and the South Vietnamese forces eventually surrendered, leading to the reunification of Vietnam under a communist government.
One of the reasons South Vietnam broke the peace agreement was because they were not satisfied with the terms of the agreement. In addition, the South Vietnamese government, led by President Nguyen Van Thieu, asked for help from the United States, but the U.S. refused to send any troops. South Vietnam was ultimately unable to withstand the North Vietnamese invasion, leading to the end of the war.