St Petersburg:
US President Barack Obama arrived in Saint Petersburg for the G20 summit in Russia, where officials said he would argue his case for military action against the Syrian regime over an alleged chemical weapons attack.
With a serious expression, Mr Obama jogged down the steps off his Air Force One plane which touched down at Saint Petersburg's Pulkovo airport ahead of the opening by Russian President Vladimir Putin of the summit later in the afternoon.
An Obama aide said there were still no plans for a bilateral between the two leaders, who are bitterly divided over Syria, but added that they would have a chance to "have interactions" on the sidelines of the meeting of heads of states of the world's biggest emerging and developed economies.
Ben Rhodes, who is Obama's Deputy National Security Advisor for Strategic Communications, said US officials will "continue to discuss with the Russian (side) what our evidentiary basis is" for claims of a chemical weapons attack by Assad's regime.
But the United States did not want to have a debate on whether the attack actually took place, he said.
Rhodes said Obama accepted that not every G20 member would agree "about the way forward in Syria, particularly given the Russian position".
He is expected to "explain our current thinking" to allies and partners and explore what type of "political and diplomatic support they may express for our efforts to hold Syrian regime accountable".
The United States has France's support for military action in Syria, but several other G20 powers including China and Germany have firmly voiced their opposition.