<Li> Hue--Da Nang </Li> <Li> Rach Chiec Bridge </Li> <Ul> <Li> Farm Gate </Li> <Li> Chopper </Li> <Li> Ranch Hand </Li> <Li> Pierce Arrow </Li> <Li> Barrel Roll </Li> <Li> Pony Express </Li> <Li> Flaming Dart </Li> <Li> Iron Hand </Li> <Li> Rolling Thunder </Li> <Li> Steel Tiger </Li> <Li> Arc Light </Li> <Li> Tiger Hound </Li> <Li> Shed Light </Li> <Li> Thanh Hoa </Li> <Li> Bolo </Li> <Li> Popeye </Li> <Li> Yen Vien </Li> <Li> Niagara </Li> <Li> Niagara II </Li> <Li> 1st Do Luong </Li> <Li> 2nd Do Luong </Li> <Li> Igloo White </Li> <Li> Giant Lance </Li> <Li> Commando Hunt </Li> <Li> Menu </Li> <Li> Patio </Li> <Li> Freedom Deal </Li> <Li> Linebacker I </Li> <Li> Enhance Plus </Li> <Li> Linebacker II </Li> <Li> Homecoming </Li> <Li> Tan Son Nhut Air Base </Li> <Li> Babylift </Li> <Li> New Life </Li> <Li> Eagle Pull </Li> <Li> Frequent Wind </Li> </Ul> <Li> 1st Do Luong </Li>

When did the us involvement in the vietnam war end