Why are there so many American trucks in Vietnam?

If it is the IWC long-head truck from the United States, it was supported by the United States in Vietnam at that time, because the United States needed Vietnam to help them transport things to the border trade zone for import and export transactions, but Vietnam at that time was really poor. The United States wants to export things, but Vietnam doesn’t have any cars to pull them to the interior of Vietnam. It wants to buy the natural resources in the interior of Vietnam, but it can’t buy them, so it chooses to support Vietnam with a group of trucks. Therefore, many American trucks are active in border trade zones in Vietnam. Locally speaking, most of the cars are Japanese, Korean, and Chinese. In fact, China also supported a batch of trucks to North Korea in the 1990s.