U.N. Secretary-General Ban Ki Moon announced Tuesday his appointment of Japan's Izumi Nakamitsu as special adviser on follow-up to a recent summit on addressing large movements of refugees and migrants.

The Sept. 19 summit, held on the sidelines of the 71st General Assembly session, was attended by the world's top diplomats to try to map a way forward in tackling the growing global problems associated with the highest number of people on the move since World War II.

Nakamitsu, who has been assistant secretary-general and assistant administrator at the U.N. Development Program's Crisis Response Unit since November 2014, replaces Karen AbuZayd of the United States, who finished out her term on Monday.

Previously, Nakamitsu served as director of the Asia and Middle East division, as well as director of the division of policy, evaluation and training with the U.N.'s peacekeeping department.

Her extensive career at the international body has included posts in and out of New York, including serving under former Secretary-General Kofi Annan as part of his reform team and at the U.N. High Commissioner for Refugees in the former Yugoslavia, Turkey and northern Iraq.