G20 Summit

Spectators watch a musical aqua show at the G20 Summit in Peterhof near St. Petersburg September 6, 2013. (REUTERS/Alexei Druzhinin/RIA Novosti)

Spectators watch a musical aqua show at the G20 Summit in Peterhof near St. Petersburg September 6, 2013. (REUTERS/Alexei Druzhinin/RIA Novosti)

Spectators watch a musical aqua show at the G20 Summit in Peterhof near St. Petersburg September 6, 2013. (REUTERS/Alexander Demianchuk)

REFILE - CORRECTING LOCATION G20 leaders attend the working dinner after their session of the G20 Summit in Peterhof, near St. Petersburg, September 5, 2013. REUTERS/Ramil Sitdikov/RIA Novosti/Pool (RUSSIA - Tags: POLITICS BUSINESS) ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS

Brazil's President Dilma Rousseff, U.S. President Barack Obama and German Chancellor Angela Merkel (L-R) arrive for the family picture event during the G20 summit in St.Petersburg September 6, 2013. REUTERS/Grigory Dukor (RUSSIA - Tags: POLITICS BUSINESS)

Russian President Vladimir Putin (L) walks past U.S. President Barack Obama (C) during a group photo at the G20 Summit in St. Petersburg September 6, 2013. At top left is British Prime Minister David Cameron. REUTERS/Kevin Lamarque (RUSSIA - Tags: POLITICS BUSINESS TPX IMAGES OF THE DAY)

U.S. President Barack Obama waves as he stands in front of British Prime Minister David Cameron during a group photo at the G20 Summit in St. Petersburg September 6, 2013. REUTERS/Kevin Lamarque (RUSSIA - Tags: BUSINESS POLITICS)

U.S. President Barack Obama (L) walks into Konstantin Palace after shaking hands with Russia's President Vladimir Putin during arrivals for the G20 summit in St. Petersburg September 5, 2013. (REUTERS/Pablo Martinez Monsivais)

U.S. President Barack Obama walks to attend the working dinner after the session of the G20 Summit in Peterhof near St. Petersburg, September 5, 2013. (REUTERS/Alexander Demianchuk)

Spectators watch fireworks and a laser show during a musical aqua show at the G20 Summit in Peterhof near St. Petersburg September 6, 2013. (REUTERS/Alexander Demianchuk)

Russia's President Vladimir Putin (L) welcomes U.S. President Barack Obama before the first working session of the G20 Summit in Constantine Palace in Strelna near St. Petersburg, September 5, 2013. REUTERS/Grigory Dukor

U.S. President Barack Obama (L) shakes hands with Japanese Prime Minister Shinzo Abe at the G20 Summit in St. Petersburg, Russia September 5, 2013. (REUTERS/Kevin Lamarque)

Japanese Prime Minister Shinzo Abe waits for U.S. President Barack Obama to arrive for their meeting at the G20 Summit in St. Petersburg September 5, 2013. (REUTERS/Kevin Lamarque)

U.S. President Barack Obama (L) meets with Japanese Prime Minister Shinzo Abe (R) at the G20 Summit in St. Petersburg September 5, 2013. (REUTERS/Kevin Lamarque)