Leaders from the G20 member countries have begun arriving in the Russian city of Saint Petersburg ahead of the two-day summit that's scheduled to start officially on Thursday. Much of the agenda may be dominated by political issues that are looming in the background.

These are hardly the images the Russian President wanted everyone discussing at the G20. Yet the escalating civil war in Syria, and talks of a looming U.S.-led strike, are now sure to steal some of the spotlight away from what's billed a summit on economics.

So too will this man, Edward Snowden. Wanted by Washington for leaking top secret documents, he's currently receiving asylum in Russia. Barack Obama is furious, and canceled a pre-summit meeting with Vladimir Putin, analysts say, signaling a new low in U.S.-Russia tension. Kremlin advisers say the two may still "talk" on the sidelines of the G20.

The same isn't being said about Japan's prime minister, Shinzo Abe, and the Chinese leader. This is Xi Jinping's first G20 as head of state. Mending recent tensions with his neighbor, sources say, is not on the agenda.

But EU politics will be. Europe's struggling banks and economies will likely get lots of attention, though Germany's Angela Merkel will surely be thinking about an election back home that's just two weeks away.

Australia's Kevin Rudd, facing a vote this week, isn't coming at all.

"They come to have a conversation about all that worries them," said Professor Daniel Alexandrov from Higher School of Economics. "And in a way, if they don't come out with a good decision about the political issues, at least they have accomplished something in the discussion of financial matters."

Indeed, Vladimir Putin will do his best to steer an economic agenda. For example, tax evasion, picking up where G8 leaders left off in northern Ireland in June; and jobs, with widespread unemployment crippling some of the world's richest economies.

"Countries are not going to play fair and nicely because there is a global competition, and in a way it's economic wars. But there have to be rules and the rules have to be set at an international conference," Alexandrov said.

The G20 presents a unique opportunity for leaders from the world's traditionally established countries and large emerging economies to work together. Or at least try. But that's easier said than done. This year's summit may prove politics to be the ultimate spoiler.