Treaty between Japan and the USA. It extended the rights granted to the USA four years earlier by the Treaty of Kanagawa, establishing diplomatic relations, accepting a conventional tariff, and granting US citizens extra-territorial rights in five treaty ports. Along with treaties signed with other foreign powers, this agreement opened the way to the westernization of Japan, but exposed the shogunate to nationalist hostility which was to play an important role in its downfall in 1868.