rex tillerson

Secretary of State Rex Tillerson says North Korea's Kim Jong Un "doesn't seem to understand diplomatic language." Vincent Thian/AP hide caption

South Korean army soldiers patrol on Monday along the barbed-wire fence in Paju, near the border with North Korea. Ahn Young-joon/AP hide caption

Tourists bow before statues of late North Korean leaders Kim Il-Sung (left) and Kim Jong-Il, in Pyongyang last month. The U.S. will ban travel to North Korea starting Sept. 1. Ed Jones/AFP/Getty Images hide caption

Secretary of State Rex Tillerson, photographed by NPR in the George C. Marshall room at the State Department in April. Ariel Zambelich/NPR hide caption

President Trump and Russian President Vladimir Putin at the G-20 Summit on Friday. Shortly after they met, the United States said the two countries had agreed to a cease-fire in southwestern Syria. Evan Vucci/AP hide caption

Otto Warmbier, a 22-year-old University of Virginia undergraduate who has been imprisoned in North Korea since January 2016, is transferred by medical personnel from a transport aircraft to an ambulance at Cincinnati Municipal Lunken Airport on Tuesday night. John Minchillo/AP hide caption

This image — taken via satellite in January 2015 — depicts what the State Department says is the crematorium at Saydnaya prison, including snowmelt on the facility's roof that acting Assistant Secretary of State for Near East Affairs Stuart Jones says is proof of the building's higher temperature. State Department/DigitalGlobe hide caption

U.S. Secretary of State Rex Tillerson, pictured in Moscow last week, says Iran has been abiding by a 2015 nuclear agreement. But he told Congress in a letter that the Trump administration was reviewing the lifting of U.S. sanctions against Iran to determine if that was in U.S. interests. Ivan Sekretarev/AP hide caption

Secretary of State Rex Tillerson shakes hands with Russian Foreign Minister Sergey Lavrov at the start of their meeting in Moscow. Russia has accused the U.S. of breaking international law with its missile strike on Syria last week. Alexander Nemenov/AFP/Getty Images hide caption

Secretary of State Rex Tillerson sits at a table surrounded by foreign ministers from G-7 countries on Tuesday, the second day of a meeting in Lucca, Italy. Tillerson headed to Moscow later that day for the start of a series of what promise to be some tough conversations. Vincenzo Pinto/AFP/Getty Images hide caption

U.S. Secretary of State Rex Tillerson waits for the start of a meeting last month at NATO headquarters in Brussels. Tillerson is scheduled to travel to Russia on Tuesday, in what promises to be a difficult round of talks after the U.S. missile strike in Syria last week. Virginia Mayo/AP hide caption