- French official: Hollande will wait for the U.S. decision before addressing the public
- The U.S. Senate could vote on whether to launch limited strikes next week
- A Syrian official says "those who lead the aggression" will pay the price
- Russia says it might support U.N. action against Syria - only if evidence is undeniable
(CNN) -- It's supposed to be a summit about the global economy, but the debate over possible military strikes against Syria will likely overshadow the G-20 conference this week.
The summit in Russia will pit two leaders with polar opposite views on Syria -- U.S. President Barack Obama, who wants to launch limited military strikes against the Syrian regime, and Russian President Vladimir Putin, whose country stands by its longtime ally in the Middle East.
The views of the 18 other countries at the G-20 run the gamut -- but could be influenced by whatever happens in St. Petersburg.
Global chess pieces
The French parliament is expected to debate military action against Syria this week. But there's not a lot of nationwide support for such an intervention -- only one in three people in France endorses punishing Syria.
President Francois Hollande will wait to hear the decision by the U.S. Congress on whether Washington will take military action on Syria before he addresses the French public directly, Foreign Minister Laurent Fabius told CNN affiliate France 2 on Thursday.
The U.S. Senate isn't expected to vote on a resolution for targeted military strikes until next week.
Read the U.S. Senate draft resolution (.pdf)
Britain, normally a dependable U.S. ally in military affairs, voted against taking any military action.
And Iran said it will defend Syria at any cost.
"We will support Syria to the end."
Calls for intervention in Syria intensified after an alleged chemical weapons attack last month left upward of 1,400 people dead, according to U.S. estimates.
Firm stances by Russia and U.S.
Russia, a strong ally of the Syrian regime and longtime arms supplier to the country, has vetoed every attempt at the U.N. Security Council to act against Syria.
But on Wednesday, Putin said he "doesn't exclude" backing a U.N. resolution for military action -- as long as there is undeniable proof Syria's government was behind the August 21 attack.
The United Nations is waiting for test results from samples taken from Syria that could indicate whether a chemical weapon attack took place. But the U.N. investigation won't conclude who was responsible.
The Obama administration has said independent tests revealed "signatures of sarin" gas in blood and hair samples from Syria, and that there is no doubt President Bashar al-Assad's regime was behind the attack.
Obama is expected to make a push for why the world needs to take action after the alleged chemical weapons attack.
"My credibility isn't on the line. The international community's credibility is on the line," Obama told reporters before flying to Russia.
"The moral thing to do is not to stand by and do nothing."
But if he doesn't muster more international support, the United States might strike on its own. Unlike with Libya in 2011, there is no U.N. Security Council agreement, nor is there a NATO-backed mission against Syria.
Warning from Syria
Syrian presidential adviser Bouthaina Shaaba warned that anyone who might strike without U.N. backing would pay a steep price.
"The Syrian people will never leave, they will always be here," Shaaban said Wednesday on Britain's Channel 4. "But those who lead the aggression will leave, and they will (live with) the results of this aggression."
The United Nations estimates more than 100,000 people have been killed in Syria since 2011, when peaceful demonstrations against the regime were met by a fierce government crackdown. The ensuing chaos spiraled into a civil war, with scores of deaths reported every day.
CNN's Jim Acosta, Chris Lawrence and Pierre Meilhan contributed to this report.
