US President Barack Obama (L) listens to Russian President Vladimir Putin (R) during the start of the G20 Working Session at the Konstantin Palace in St Petersburg Sept 5, 2013. Also pictured are Indonesian President Susilo Bambang Yudhoyono (2nd L), and Australian Foreign Minister Bob Carr (2nd R). [Photo/Agencies]

Russian President Vladimir Putin (L) and US President Barack Obama are pictured on a video screen installed in the press centre of the G20 Summit in Strelna near St Petersburg, Sept 5, 2013. [Photo/Agencies]