<Ul> <Li> Ban Houei Sane </Li> <Li> Lang Vei </Li> </Ul> <Li> Ban Houei Sane </Li> <Li> Phase One Offensive <Ul> <Li> Saigon </Li> <Li> US Embassy </Li> <Li> Cholon and Phu Tho Racetrack </Li> <Li> Tan Son Nhut Air Base </Li> <Li> Joint General Staff Compound </Li> <Li> Bien Hoa and Long Binh </Li> <Li> Hue </Li> <Li> Quảng Trị </Li> <Li> Coburg </Li> <Li> Lo Giang </Li> </Ul> </Li> <Ul> <Li> Saigon </Li> <Li> US Embassy </Li> <Li> Cholon and Phu Tho Racetrack </Li> <Li> Tan Son Nhut Air Base </Li> <Li> Joint General Staff Compound </Li> <Li> Bien Hoa and Long Binh </Li> <Li> Hue </Li> <Li> Quảng Trị </Li> <Li> Coburg </Li> <Li> Lo Giang </Li> </Ul>

4. what happened in vietnam after the u.s. left vietnam