Debates over Syria's civil war and the potential of U.S. military strikes there are expected to overshadow a meeting of world leaders beginning Thursday in Russia.
The Syrian crisis is not on the official agenda for the two-day Group of 20 global economic summit in Saint Petersburg, but leaders are expected to discuss it on the sidelines.
U.S. President Barack Obama is seeking broader support, both at home and abroad, for military strikes against Syria's government for allegedly using chemical weapons on its civilians.
A day before the G20 summit, a key U.S. Senate panel approved a plan that would call for limited strikes lasting no more than 90 days. The measure, which also rules out deploying U.S. ground troops to Syria, must still pass both houses of Congress.
Mr. Obama said Wednesday during a visit to Sweden that the credibility of the international community is on the line if it does not respond to the actions of Syrian President Bashar al-Assad.
Russia, Syria's main supplier of arms, and China have already vetoed three U.N. Security Council resolutions that would have punished President Assad's government.
Speaking ahead of the summit, Chinese Vice Foreign Minister Zhu Guangyao said Thursday any military action against Syria would cause a hike in oil prices and have a "negative impact" on the global economy.
On Wednesday, Russian President Vladimir Putin warned Western strikes without U.N. Security Council approval would be an unacceptable "aggression." But he said he would support a strike if there were "convincing" proof that Damascus used chemical weapons.
U.S. intelligence says over 1,400 people died last month in a sarin nerve gas attack on a Damascus suburb controlled by opponents of Mr. Assad. The White House says the attack was carried out by the government. Syria denies this, saying any poison gas was used by rebels.
Tens of thousands of people have died in Syria's two and a half year-long civil war, which began as a peaceful protest against the authoritarian rule of President Assad.
Even as the U.S. pushes for possible strikes, U.N. officials continue to look for a political settlement to the conflict. Officials say U.N.-Arab League envoy on Syria Lakhdar Brahimi is headed to St. Petersburg to help U.N. chief Ban Ki-moon organize a Syrian peace conference.