If you are in Vietnam then the US Embassy in Vietnam is located in the city of Hanoi. Note the contact details for the Embassy listed below as well as the contact details for the US Consulate in Ho Chi Minh City. You can ask about assistance as an American if you are in need of consular assistance.
The US Embassy in Vietnam does not deal with question about the US fiancee visa or the US marriage visa or even the K2 visa. You are best advised to seek assistance from a law firm in Vietnam for this.
US Embassy in Hanoi
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US Consulate Ho Chi Minh City
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