Eagles Over the Kennebec

Current reading is Madame Sadayakko: The Geisha Who Bewitched the West by Lesley Downer. In it, I learn that Sada was four or five when Commodore Perry came in his black ships to force Japan to open itself to the rest of the world (and cut the Dutch out of a trade monopoly, not that the US would have worried any about that, ahem). What I don't remember (if I ever knew) is how Perry (or, if you like, Millard Fillmore, who had been my favorite president until I found out late in high school that he hadn't done nothing during his term) had the leverage (gall and/or chutzpah) to demand that Japan open its borders. I do understand that the ships came at ...an opportune time, as the shogunate was starting to deteriorate, but surely the motive could not have been to prevent the messy collapse of the Japanese government, especially since the influx of Westerners and Western Stuff sent the culture and the politics into a tailspin, anyway.

Japan had withdrawn from the world; it was backward, insular, politically inept, and a sovereign nation. So, where did the US get the moral standing to demand the opening of borders and trade?