U.S.-RUSSIA
Obama and Russian President Vladimir Putin have grappled with Russia's actions in Ukraine and other issues straining ties such as Syria and Iran in meetings on the sidelines of other summits, while putting on smiles for the cameras in the wider gatherings. Relations remain tense, as a truce between pro-Russian rebels and Ukraine's government wobbles, and the U.S. threatens to expand sanctions that have shaken the Russian economy. Putin, meanwhile, underlined his presence at the G-20 summit with the stationing of four Russian warships in international waters of Australia's northeastern coast, prompting a scathing critique from Australian prime minister Tony Abbott.