how an inevitable error on either sheng 's or his assassin 's part could bring about an explosion so drastic that troops from the people 's republic could move into hong kong within hours , bringing not only the colony 's world trade to a halt , but with it widespread human suffering -savage rioting everywhere , death squads from the left and the right exploiting resentments going back forty years , racial and provincial factions pitted against one another and the military forces .