British Prime Minister Theresa May meets with United Nations Secretary-General Antonio Guterres on the sidelines of the 72nd United Nations General Assembly at U.N. Headquarters in Manhattan, New York, U.S., September 19, 2017.

Turkish President Recep Tayyip Erdogan signs a guest book just before a meeting with United Nations Secretary-General Antonio Guterres on the sidelines of the 72nd United Nations General Assembly at U.N. Headquarters in Manhattan, New York, U.S., September 19, 2017.

U.S. President Donald Trump addresses the 72nd United Nations General Assembly at U.N. headquarters in New York, U.S., September 19, 2017.

Russian Foreign Minister Sergey Lavrov arrives at the 72nd United Nations General Assembly at U.N. Headquarters in New York, U.S., September 19, 2017.

Turkish President Recep Tayyip Erdogan addresses the 72nd United Nations General Assembly at U.N. headquarters in New York, U.S., September 19, 2017.

U.S. President Donald Trump meets French President Emmanuel Macron in New York, U.S., September 18, 2017.

U.S. President Donald Trump addresses the 72nd United Nations General Assembly at U.N. headquarters in New York, U.S., September 19, 2017.

French President Emmanuel Macron addresses the 72nd United Nations General Assembly at U.N. headquarters in New York, U.S., September 19, 2017. Reuters/Lucas Jackson

U.S. President Donald Trump participates in a session on reforming the United Nations at UN Headquarters in New York, U.S., September 18, 2017.

Egyptian President Abdel Fattah Al Sisi addresses the 72nd United Nations General Assembly at U.N. Headquarters in New York, U.S., September 19, 2017.

Ivanka Trump, speaks during a meeting on action to end modern slavery and human trafficking with Guy Ryder, director general of the International Labour Organizationon and Andrew Forrest, Chairman of Fortescue Metals Group and the Minderoo Foundati on the sidelines of the 72nd United Nations General Assembly at U.N. Headquarters in Manhattan, New York, U.S., September 19, 2017.

United Nations Secretary General Antonio Guterres addresses the 72nd United Nations General Assembly at U.N. headquarters in New York, U.S., September 19, 2017.