. ▁While ▁Japan ▁and ▁China ▁had ▁in ▁fact ▁opened ▁diplom atic ▁relations ▁in ▁ 1 9 7 2 , ▁the ▁peace ▁treat y ▁took ▁nearly ▁six ▁years ▁to ▁negoti ate , ▁one ▁major ▁stick ing ▁point ▁being ▁Chinese ▁ins istence ▁on ▁Tokyo ▁including ▁a ▁clause ▁that ▁den ounced ▁Soviet ▁" he gem ony " ▁in ▁Asia . ▁ ▁There ▁was ▁little ▁sign ▁of ▁improved ▁relations ▁with ▁the ▁Soviet ▁Union , ▁and ▁D eng ▁X ia op ing ▁declared ▁the ▁ 1 9 5 0 ▁S ino - S ov iet ▁friendship ▁treat y ▁to ▁be ▁null ▁and ▁void . ▁Rel ations ▁with ▁Vietnam ▁suddenly ▁turned ▁host ile ▁in ▁ 1 9 7 9 . ▁These ▁two ▁countries ▁had ▁once ▁been ▁al lies , ▁but ▁in ▁ 1 9 7 2 ▁Ma o ▁Z ed ong ▁told ▁Vietnam ese ▁premier ▁Ph am ▁Van ▁D ong ▁that ▁they ▁should ▁stop ▁expecting ▁Chinese ▁aid ▁and ▁that ▁the ▁old ▁historical ▁fe ud ▁between ▁the ▁two ▁countries ▁would ▁er upt ▁again . ▁China ▁also ▁gave ▁its ▁support ▁to ▁the ▁gen oc idal ▁Kh mer ▁Rou ge ▁regime ▁that ▁took ▁power ▁in ▁Camb odia ▁during ▁ 1 9 7 5 , ▁prov oking ▁the ▁host ility ▁of ▁the ▁Soviet - back ed ▁Vietnam ese ▁government . ▁In ▁January ▁ 1 9 7 9 , ▁Vietnam ▁inv aded ▁Camb odia ▁and ▁drove ▁the ▁Kh mer ▁Rou ge ▁from ▁power . ▁During ▁his ▁U . S . ▁visit , ▁D eng ▁X ia op ing ▁remarked ▁that ▁Vietnam ▁would ▁have ▁to