Major issues regarding the Philippines and Korea were clarified at a high level in 1905 in the Taft–Katsura Agreement, with the United States acknowledging Japanese control of Korea, and Japan recognizing American control of the Philippines. The two nations cooperated with the European powers in suppressing the Boxer Rebellion in China in 1900, but the U.S. was increasingly troubled about Japan's denial of the Open Door Policy that would ensure that all nations could do business with China on an equal basis. President Theodore Roosevelt played a major role in negotiating an end to the war between Russia and Japan in 1905–6.