"No Japanese ship shall leave for foreign countries. No Japanese shall go abroad secretly. If any Japanese returns from overseas after residing there, he must be put to death. All foreign trade shall be conducted only at Nagasaki, under the strict supervision of the shogunal officials."

— Tokugawa Iemitsu, Sakoku Edict, 1635

Question: The Sakoku Edict of 1635 MOST directly served which of the following Tokugawa political goals?