I have visited the Vietnamese capital Hanoi twice, each time staying for over a month. Despite the busy traffic in Hanoi, my overall impression is that the security is good. I have gone out alone for a few late night rides without encountering any safety issues. In Hanoi, I have not heard of multiple incidents of fighting or crime, which makes me feel relatively safe.
There are many foreign residents in Hanoi who take a walk around Huanjian Lake at night and can hear multiple languages such as English, Chinese, Korean, and Japanese. This shows that Vietnamese people are not exclusive to foreigners. Vietnamese lovers and foreign tourists can often be seen on the lakeside to enjoy this romantic place together.