Obama's presence at the Group of 20 gathering in Russia highlights his tense relationship with Russian President Vladimir Putin, an ally of Syrian President Bashar Assad.
"It's been like watching a slow-moving train wreck for nearly two years," Andrew Kuchins, a Russia expert at the Center for Strategic and International Studies, said of the Obama-Putin relationship. "Mr. Putin and Mr. Obama don't like each other at all. I think there's a deep degree of disrespect."
His surprise announcement over the weekend that he would seek congressional authorisation for a military strike against Syria may have stoked doubts among world leaders about his willingness to make good on his threats to rogue nations.
His administration argues that the strike is needed in response to what it says was a deadly chemical weapons attack last month.
Before a White House meeting today with lawmakers whose votes he will need, Obama said he is confident he will be able to work with Congress to pass a resolution authorising the strike on Syria. Obama indicated that he's open to changes to his request for congressional authorisation, which he said must send a clear message to Assad and hamper his ability to use chemical weapons.
Obama spoke about Syria ahead of the meeting by telephone last night with Japanese Prime Minister Shinzo Abe, the White House said today. A White House statement said Obama and Abe pledged to consult on a possible international response.
