Answer:
He could return with a larger force and attack Japan.
Step-by-step explanation:
In the letter shown above, the author calmly states that the USA and its four small ships are in Japan, for a friendly and peaceful mission, however, they intend to make proposals to the presidents of Japan that, if not accepted, will provoke the United States to send a much larger military force than the one currently sent. This larger military force will not have a peaceful nature and will attack Japan if the Japanese president is not cooperative.