U.S. Trade Representative Robert Lighthizer speaks during a press conference after the seventh round of talks to modernize the North American Free Trade Agreement (NAFTA), in Mexico City, capital of Mexico, on March 5, 2018. The seventh round of talks to modernize NAFTA ended here Monday on a mixed note with the U.S. calling the progress not good enough but Mexico remaining upbeat. (Xinhua/Francisco Canedo)