Explain how did commodore perry's actions in japan represent a change in u. s. foreign policy?

           Commodore Matthew Perry was dispatched to Japan by US president Millard Filmore. Perry was in command of 4 warships. His fleet arrived near the Tokugawa capital of Edo on July 8, 1853. Japan at that time was ruled by the shogun ( "great general" ) from Tokugawa family. In the 17th century the 3rd shogun enforced isolation of Japan from the rest of the world. 
            Perry`s primary goal was to force an end to Japan`s policy of isolation and open Japanese ports to American trade. This was the era when all Western powers were seeking to open new markets for their goods abroad. Finally the emperor of Japan agreed to the demands.
           The maritime expansion across the Pacific Ocean had important implications for US foreign policy. It changed the global position of the United States.

It can provide a social code to protect each citizen's future economical earnings. and then obviously defending the country from invading countries.