Antonio Guterres took the oath of office on Monday (Dec 12)as the United Nations’ new secretary-general during a formal ceremony at the General Assembly.
He pledged to “exercise in all loyalty, discretion and conscience” his duties as UN chief when he takes over from Ban Ki-moon on January 1.
He also vowed  to carry out reforms to improve the world body.
“The UN must be ready to change,” He said.