The sanitation of China means the elimination of the Chinese population.  Many people believe that "The Unparalleled Invasion" shows that Jack London was in favor of genocide.  I find that hard to believe based on what I have read in his other books, but I have not read everything.  It seems more like a cautionary tale than anything else.  I do not see how London could have been in favor of the United States and other countries wiping out the Chinese population.