Answer: I would characterize the U.S. involvement in Vietnam as a failure of American foreign policy.
Explanation: The US caused a lot of their own troops to die and left several behind. They also gassed Vietnam which caused a lot of environmental damage, birth defects, deaths,cancers, and deaths. On the whole, the US failed their citizens and caused a lot of innocent people to be killed thus characterizing this as a failure of foreign policy.
Answer: Throughout the US history, we have opened the doors for them, allowing them in the states, and other times we slam the door on them, and telling them to leave. We have a complex relationship with them, but they are shaping all we are doing!