Trump shares a laugh with German Chancellor Angela Merkel during a women's entrepreneurship finance event July 8 at the G20. Evan Vucci/AP

Ivanka Trump and US Treasury Secretary Steven Mnuchin are on hand as the President arrives for the G20's morning working session on July 8. Sean Gallup/Getty Images

European Commission President Jean-Claude Juncker and Trump chat before the morning working session July 8. Sean Gallup/Getty Images

Trump attends a banquet after a concert of the Hamburg Philharmonic State Orchestra on Friday, July 7, as part of the events at the two-day summit. KAY NIETFELD/AFP/Getty Images

Germany's Merkel, center, right, hosts the banquet. At top right, Russian President Vladimir Putin sits next to US first lady Melania Trump. Donald Trump, bottom, left, across from Chinese President Xi Jinping. TOBIAS SCHWARZ/AFP/Getty Images

The Trumps join French President Emmanuel Macron and his wife, Brigitte, at the Elbphilharmonie concert hall in Hamburg on July 7. CHRISTIAN CHARISIUS/AFP/Getty Images

Trump joins world leaders and their partners as they pose for photos before the concert. Stefan Rousseau/Pool/Getty Images

Trump shakes hands with Putin as they meet on the sidelines of the summit. They talked for more than two hours, discussing interference in US elections and ending with an agreement on curbing violence in Syria. Evan Vucci/AP

World leaders gather for a photo at the summit. The G20, which includes 19 countries and the European Union, accounts for about 80% of the world's gross domestic product. ODD ANDERSEN/AFP/Getty Images

Trump stands with Putin and European Commission President Jean-Claude Juncker, left, at the G20 summit. Climate change, terrorism and migration are on the agenda. BPA via Getty Images

Trump greets Putin as the G20 summit gets underway in Hamburg. Steffen Kugler/BPA via Getty Images

Macron, Merkel and Trump confer at the start of the first working session of the G20 summit. JOHN MACDOUGALL/AFP/Getty Images

Trump meets with Merkel on the eve of the summit. MICHAEL KAPPELER/AFP/Getty Images

Trump reaffirms US support for NATO in a speech he gave in Warsaw, Poland, on Thursday, July 6. Trump spent a day in Poland before heading to Germany. Petr David Josek/AP

People hold up pictures of Trump during his speech in Warsaw. Artur Widak/Sipa USA/Newscom

Trump joins world leaders from the Three Seas Initiative, an alliance of Eastern European countries, at the Royal Castle in Warsaw on July 6. SAUL LOEB/AFP/Getty Images

Trump holds a joint news conference with Polish President Andrzej Duda on July 6. SAUL LOEB/AFP/Getty Images

First ladies Melania Trump and Agata Kornhauser-Duda play with children as they visit the Copernicus Science Centre in Warsaw on July 6. ANDRZEJ HULIMKA/AFP/Getty Images

Duda and Trump meet at the Royal Castle in Warsaw on July 6. SAUL LOEB/AFP/Getty Images