Eu acredito que você está se referindo a " Black Star Rising " por Frederick Pohl.
When a mysterious alien spacecraft approaches the Earth and demands to speak with the President of the United States, then destroys a large Pacific island to demonstrate its strength and its seriousness, you'd expect the President to talk. Problem is, in the late twenty-first century, there is no President--not even a United States. China rules the Americas, and to most people "US" and "USSR" are just quaint abbreviations in historical dictionaries. But the aliens prove unreasonable about accepting substitutes. So one Anglo rice-cultivator from the Heavenly Grain Collective farm near Biloxi, Mississippi is forced to begin an adventure that will take him from peasant to President, from Pettyman to Spaceman.