▁Ind och ina ▁into ▁the ▁Kingdom ▁of ▁La os , ▁the ▁Kingdom ▁of ▁Camb odia , ▁South ▁Vietnam , ▁and ▁North ▁Vietnam , ▁the ▁latter ▁of ▁which ▁was ▁controlled ▁by ▁the ▁Commun ist ▁V iet ▁Min h . ▁The ▁Vietnam ▁War ▁began ▁in ▁ 1 9 5 5 ▁as ▁North ▁Vietnam ese ▁forces , ▁with ▁the ▁support ▁of ▁the ▁Soviet ▁Union , ▁China , ▁and ▁other ▁Commun ist ▁govern ments , ▁sought ▁to ▁reun ify ▁Vietnam ▁by ▁taking ▁control ▁of ▁South ▁Vietnam . ▁Under ▁President ▁Eisen h ower , ▁who ▁sought ▁to ▁prevent ▁the ▁spread ▁of ▁Commun ism ▁in ▁S out heast ▁Asia , ▁the ▁United ▁States ▁replaced ▁France ▁as ▁the ▁key ▁patron ▁of ▁South ▁Vietnam . ▁Eisen h ower ▁and ▁Kennedy ▁both ▁dispatch ed ▁U . S . ▁military ▁advis ers ▁to ▁South ▁Vietnam , ▁and ▁by ▁the ▁time ▁Johnson ▁took ▁office , ▁there ▁were ▁approximately ▁ 1 6 , 7 0 0 ▁American ▁military ▁personnel ▁in ▁South ▁Vietnam . ▁Despite ▁some ▁mis giv ings , ▁Johnson ▁ultimately ▁came ▁to ▁support ▁es cal ation ▁of ▁the ▁U . S . ▁role ▁in ▁Vietnam . ▁He ▁fe ared ▁that ▁the ▁fall ▁of ▁Vietnam ▁would ▁hurt ▁Democratic ▁cred ibility ▁on ▁national ▁security ▁issues , ▁and ▁he ▁also ▁wanted ▁to ▁carry ▁on ▁what ▁he ▁saw ▁as ▁Kennedy ' s ▁policies . ▁Finally , ▁like ▁the ▁vast ▁majority ▁of ▁U . S . ▁political ▁leaders ▁in ▁the ▁mid - 1 9 6 0 s , ▁he ▁was ▁determined ▁to ▁prevent ▁the ▁spread ▁of ▁Commun ism .