Rebecca Lissner is a Senior Fellow for U.S. Foreign Policy at the Council on Foreign Relations. She served as a deputy assistant to the president and principal deputy national security advisor to the vice president in the Biden-Harris administration.
TOPSHOT - US President Donald Trump takes his place for the family photo on the first day of the G20 summit in Hamburg, northern Germany, on July 7, 2017.
Leaders of the world's top economies gather from July 7 to 8, 2017 in Germany for likely the stormiest G20 summit in years, with disagreements ranging from wars to climate change and global trade. / AFP PHOTO / SAUL LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)
HEMPSTEAD, NY - SEPTEMBER 26: Republican presidential nominee Donald Trump stands at his podium during the Presidential Debate at Hofstra University on September 26, 2016 in Hempstead, New York. The first of four debates for the 2016 Election, three Presidential and one Vice Presidential, is moderated by NBC's Lester Holt. (Photo by Win McNamee/Getty Images)
