Since the G20 first met five years ago to urgently deal with the global financial crisis, its meetings have tended to become more routine and yield diminishing results. The G20 meeting in St. Petersburg on Sept 5-6, however, will be different because of the international political context.

The abrupt halt to a scheduled US-Russia summit in Moscow and further escalation of the Syrian civil war after the alleged use of chemical weapons and the likely United States-led military intervention in Syria have pushed security issues to the top of the world leaders' agenda. The timing will turn the gathering of heads of state and government into a more important event.

Summits are as much about the personalities of summiteers as they are about the states they represent. US President Barack Obama is known for his trademark impersonal style of dealing with other countries' leaders. But his recent public comments on Russian President Vladimir Putin suggest they don't enjoy a cordial relationship. The cancellation of the US-Russia summit, which would have preceded the G20 meeting, marks the end of a collaborative phase in Russo-American relations.