Russian opposition leader Alexei Navalny, with daughter Daria (right) and son Zakhar (left), prepares to vote in the mayoral election in Moscow on Sunday, Sept. 8, 2013. (AP Photo/Sergei Grits)
President Obama gestures while speaking during a "Civil Society Roundtable" with gay, lesbian, bisexual and transgender activists, Friday, Sept. 6, 2013, in St. Petersburg, Russia. (AP Photo/Pablo Martinez Monsivais)
President Obama pauses as he answers a question regarding the ongoing situation in Syria during his news conference at the G-20 Summit in St. Petersburg, Russia, on Sept. 6, 2013. (Associated Press)
President Obama pauses as he answers a question regarding the ongoing situation in Syria during his news conference at the G-20 Summit in St. Petersburg, Russia, on Sept. 6, 2013. (Associated Press)
** FILE ** Russia's President Vladimir Putin speaks during a media conference after a G-20 summit in St. Petersburg, Russia on Friday, Sept. 6, 2013. (AP Photo/Alexander Zemlianichenko)
U.S. President Barack Obama, left, and China's President Xi Jinping, right, shake hands before their bilateral meeting at the G-20 Summit, Friday, Sept. 6, 2013 in St. Petersburg, Russia. (AP Photo/Pablo Martinez Monsivais)
"The international community's credibility is on the line" with Syria, President Obama says during a news conference in Stockholm on Wednesday, a day before traveling to Russia for a Group of 20 summit. (Associated Press)
Russian President Vladimir Putin (right) and Deputy Prime Minister Dmitry Rogozin attend a meeting while visiting the Rostvertol helicopter manufacturing company in Rostov-on-Don, Russia, on Thursday, Aug. 22, 2013. (AP Photo/RIA-Novosti, Alexei Nikolsky, Presidential Press Service)
Jamaica's Usain Bolt, right, goes to cross the finish line ahead of United States' Justin Gatlin, second from right, and Germany's Martin Keller in the women's 4x100-meter relay final at the World Athletics Championships in the Luzhniki stadium in Moscow, Russia, Sunday, Aug. 18, 2013. (AP Photo/Matt Dunham)
United States' Matthew Centrowitz celebrates winning the silver in the men's 1500-meter final at the World Athletics Championships in the Luzhniki stadium in Moscow, Russia, Sunday, Aug. 18, 2013. (AP Photo/Matt Dunham)