The acquisition of the Southwest had made the United States a Pacific power. Diplomatic and commercial ties with China had been first established in 1844, and American merchants and shippers began urging an opening of ties with Japan, a country that had virtually isolated itself from the outside world for the past 300 years. In 1853, a fleet commanded by Commodore Matthew C. Perry arrived in Japan and forced the shogunate to sign a treaty with US, although Japanese fears of Russian encroachment also moved matters along.