How did the League of Nations respond to Japanese aggression in China? Responses by sending in troops to stop aggressive Japanese expansion attempts by sending in troops to stop aggressive Japanese expansion attempts by protesting the actions, which proved ineffective in stopping the aggression by protesting the actions, which proved ineffective in stopping the aggression by punishing and putting a military end to Japanese aggression by punishing and putting a military end to Japanese aggression by negotiating a deal for Japan to back down in exchange for money