Australian Prime Minister Tony Abbott (L) shakes hands with Russian President Vladimir Putin as he officially welcomes leaders to the G20 summit in Brisbane November 15, 2014. A showdown between Western leaders and Putin is likely at the G20 summit in Australia starting on Saturday, following fresh reports of Russian troops pouring into eastern Ukraine. REUTERS/David Gray (AUSTRALIA – Tags: POLITICS BUSINESS TPX IMAGES OF THE DAY PROFILE) – RTR4E8FL