Incompetent leadership, domestic political unrest and lack of adequate transportation facilities contributed to Russia's defeat in the war with Japan. An offer by the American president, Theodore Roosevelt, to mediate an end to hostilities was gratefully accepted by both sides - the Japanese were facing increasing difficulty supplying their army's advance. Negotiations were held in Portsmouth, New Hampshire and formally concluded with the Treaty of Portsmouth in September 1905.
Roosevelt's role in the international agreement signaled the emergence of the United States as a world power. The treaty also marked the end of Tsarist Russia's expansion in the Far East. Japan was given the [M 040 / Liaotung Peninsula] and southern half of Sakhalin Island in addition to railway rights over southern Manchuria as far as Changchun. Russia was also forced to acknowledge Japanese hegemony in Korea. In November that same year Japan assumed responsibility for Korea's foreign policy and formally annexed the country in August 1910.
