U.S. President Barack Obama (R) greets Columbia's President Juan Manuel Santos Calderon as he arrives for a luncheon during the United Nations General Assembly at United Nations headquarters in New York City, U.S. September 20, 2016. REUTERS/Lucas Jackson

King Don Felipe VI of Spain greets U.S. President Barack Obama (R) as he arrives for a luncheon during the United Nations General Assembly at United Nations headquarters in New York City, U.S. September 20, 2016. REUTERS/Lucas Jackson

U.S. President Barack Obama toasts as UN Secretary General Ban Ki-moon listens at a luncheon during the United Nations General Assembly at United Nations headquarters in New York City, U.S. September 20, 2016. REUTERS/Lucas Jackson

Qatar's Emir, Sheikh Tamim bin Hamad al-Thani greets U.S. President Barack Obama (L) as he arrives for a luncheon during the United Nations General Assembly at United Nations headquarters in New York City, U.S. September 20, 2016. REUTERS/Lucas Jackson

A man walks past a display of the Nikkei average and other market indices outside a brokerage in Tokyo, Japan April 19, 2016. REUTERS/Thomas Peter

Chinese Premier Li Keqiang speaks during a High Level Leaders meeting on Refugees on the sidelines of the United Nations General Assembly at United Nations headquarters in New York, U.S. September 20, 2016. REUTERS/Brendan McDermid

British Prime Minister Theresa May enters the General Assembly Hall to speak during the 71st United Nations General Assembly in Manhattan, New York, U.S. September 20, 2016. REUTERS/Eduardo Munoz

Ukraine's President Petro Poroshenko (R) greets British Prime Minister Theresa May as he arrives for a luncheon during the United Nations General Assembly at United Nations headquarters in New York City, U.S. September 20, 2016. REUTERS/Lucas Jackson