ic ▁Co operation ▁( Come con ) ▁and ▁signed ▁the ▁Tre aty ▁of ▁Friend ship ▁and ▁Co operation ▁with ▁the ▁Soviet ▁Union ▁in ▁ 1 9 7 8 , ▁China ▁brand ed ▁Vietnam ▁the ▁" C uba ▁of ▁the ▁East " ▁and ▁called ▁the ▁treat y ▁a ▁military ▁al liance . ▁Inc idents ▁along ▁the ▁S ino - V ietnam ese ▁border ▁increased ▁in ▁frequency ▁and ▁violence . ▁In ▁December ▁ 1 9 7 8 ▁Vietnam ▁inv aded ▁Camb odia , ▁quickly ▁ou sted ▁the ▁pro - M ao ▁Pol ▁Pot ▁regime , ▁and ▁over ran ▁the ▁country . ▁ ▁China ' s ▁twenty - n ine - day ▁inc urs ion ▁into ▁Vietnam ▁in ▁February ▁ 1 9 7 9 ▁was ▁a ▁response ▁to ▁what ▁China ▁considered ▁to ▁be ▁a ▁collection ▁of ▁provoc ative ▁actions ▁and ▁policies ▁on ▁H ano i ' s ▁part . ▁These ▁included ▁Vietnam ese ▁int im acy ▁with ▁the ▁Soviet ▁Union , ▁mist re at ment ▁of ▁eth nic ▁Chinese ▁living ▁in ▁Vietnam , ▁h eg emon istic ▁" imper ial ▁dream s " ▁in ▁S out heast ▁Asia , ▁and ▁sp urn ing ▁of ▁Be ij ing ' s ▁attempt ▁to ▁rep atri ate ▁Chinese ▁residents ▁of ▁Vietnam ▁to ▁China . ▁In ▁February ▁ 1 9 7 9 ▁China ▁attacked ▁along ▁virt ually ▁the ▁entire ▁S ino - V ietnam ese ▁border ▁in ▁a ▁brief , ▁limited ▁campaign ▁that ▁involved ▁ground ▁forces ▁only . ▁The ▁Chinese ▁attack ▁came ▁at ▁dawn ▁on ▁the ▁morning ▁of ▁ 1