During the mid to late 1800s, the Japanese Shogunate expanded into the Pacific Ocea, colonising northern Sakhalin Island, Guam, Micronesia and other smaller islands. After the American, British and Californian navies aided in the opening of Japanese ports to the world, after the Japanese threw away the Sakuko Law that banned foreigners from entering Japan. The Japanese Empire signed various trade and treaties with the Western Powers, specifically California, the United Kingdom (via the Anglo-Japanese Treaty of Friendship in 1854) and the United States. Japan's rapid expansion into the Pacific Ocean was seen by the Russian Empire as a threat to their soverignty. After the Sino-Japanese War of 1860, the Japanese annexed parts of Manchuria and Korea, giving them a foothold onto mainland Asia, frightenting the Russians even more. This is seen as one of the predominant reasons of why Russia began to drift over to the German Sphere of influence. China later went into isolation until the turn of the 20th century.
For more information see: Japanese War