With the death of President Franklin D. Roosevelt on April 12, 1945, Vice President Harry S. Truman assumed the Oval Office. He surely knew he faced a difficult set of challenges in the immediate future: overseeing the final defeats of Germany and Japan; managing the U.S. role in post-war international relations; supervising the American economy's transition from a war-time to a peace-time footing; and maintaining the unity of a fractious and powerful Democratic Party.
If the border with Laos had been closed and North Vietnam had not been able to operate in the country, the communist side would not have been able to stock up on resources, men, ammunition, weapons, food and medicine through the HoChi Minh Trail.
Therefore, the forces of the North that were fighting in South Vietnam would have been out of supply, and their defeat would have been imminent.
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